Eh, I don't miss them.
Sure, the themes from The Addams Family, the Beverly Hillbillies/Petticoat Junction/Green Acres shared universe--or as I like to call it, the Hooterverse--and The Fresh Prince of Bel-Air are lovable classics. In fact, you can hear the Fresh Prince theme in its entirety, complete with Will Smith's forgotten bars about flying first class (which were in the opening titles for only the first few episodes and then were removed), either during "Beat Box" and "The Whitest Block Ever" on AFOS or right below. But I like how stripped-down broadcast network TV is these days compared to how TV was when I was a kid.
As Andy Greenwald once wrote over at Grantland, the very '80s L.A. Law opening credits are a slow 90 seconds of random clips of people leaving meetings, carrying briefcases and shrugging. Broadcast network TV used to be so slow-paced that shows like Misfits of Science in the '80s and The Wayans Bros. in the '90s got to open with two themes in the same sequence.
The gradual elimination of opening themes from broadcast TV--to accommodate more ad space, as well as to keep fidgety viewers from channel-switching and to somewhat emulate modern-day cinematic blockbusters that have done away with opening credits altogether--took some adjustment for a couple of years, but I'm used to it by now. It won't be long before I spot yet another link to an article from the olds about how TV was better in my day because we had opening themes that were 22 minutes long and so on. No, it wasn't, Grumpy Old Man from Weekend Update. A huge chunk of pre-Sopranos/Wire, pre-niche-programming TV hasn't aged well. (As much as I love the timeless Taxi, there are still some things about it that haven't stood the test of time, like the cheesy product placement for Jeff Conaway's pop album debut during Taxi's "Fantasy Borough" two-parter. Remember that album? Because I don't.)
That's partly what Adult Swim's immensely popular "Too Many Cooks" short is making fun of: all those poor-quality clips of absurdly-lengthy-by-today's-standards opening title sequences from ancient shows that we often watch on YouTube with cringes or "Oh God, for real? This was a thing?"-ish looks on our faces. For example, I don't think my ears will be able to withstand hearing the mega-sappy and mega-anachronistic Joanie Loves Chachi theme on YouTube again. So there's one benefit to phasing out opening themes: never again will someone compose for a network show's opening titles something as abominable and interminable as the Joanie Loves Chachi theme. Never again will someone recycle the theme from Patch Adams (place Sideshow Bob shudder here).
On broadcast TV, almost all the good theme tunes that used to be allowed to breathe at the start of the show are being saved for the end credits. But you have to be a cord-cutter or a subscriber to either Hulu Plus or Netflix in order to hear those end title themes because on Hulu or Netflix, they're not squeezed out by a trailer for next week's episode or a network promo for another show, a network practice I find to be way more annoying than the elimination of opening themes.
"Penguin's Umbrella," the strongest hour so far of this rather mixed bag of a show--brings to mind both the Dragnet march and Ennio Morricone's work on The Untouchables, with a little bit of Bear McCreary's opening theme from DC Entertainment's one-season wonder Human Target (yeah, there was a second season, but I like to pretend it never happened) in there.
TV theme purists, there's a place where you can enjoy as many lengthy opening themes as you want. It's called premium cable. That's where the art of setting the mood with a distinctive melody has been lovingly preserved. The showrunners of ad-free shows like Game of Thrones and True Detective are free to do whatever they want, and that includes taking as much time as they please in setting the mood, whether it's Ramin Djawadi--with the help of a lavish 3-D map--grandly re-acclimating viewers each week to the power struggle in Westeros or The Handsome Family's 2003 Southern Gothic song "Far from Any Road" (which is amusingly parodied in Key & Peele's current opening titles) establishing the haunted landscapes of Hart and Cohle's home state of Louisiana.
There's another place where lengthy opening themes haven't died out. It's called Japan. Every animated show over there opens with a J-pop song that the anime crowd simply calls an "OP" and ends with a completely different tune for the end credits that's known as an "ED." The same goes for any animated show in America except The Venture Bros. and Regular Show. Bob's Burgers currently kicks off with one of the best mood-setting themes in animation, a ukulele piece accented with xylophone and Casio keyboard FX, in much the same fashion as a burger getting accented with often outré ingredients or toppings by Bob, although I wish it were allowed to run longer at the start of the show. On the Song Exploder podcast, Bob's Burgers creator Loren Bouchard went into detail about how he composed the show's opening theme, which he also revealed is actually a much longer composition than what we currently hear on the show. He said, "I wanted a little bit of hope and optimism in the music. This had to be a story of hardship as it pertains to running a restaurant, but it's supposed to be an optimistic show and a nice slice of life with a lot of happiness in it. The ukulele was perfect, so I knew that I wanted to start with that."
Advertisers (along with network researchers who took note of viewers who changed the channel right when an opening theme began) aren't all to blame for the elimination of opening themes or the shortening of themes like Bouchard's optimistic table-setter. Blame Wings too. Now I always liked Wings--don't get it twisted (and if you don't laugh during the William Hickey or Phil Leeds episodes of Wings that are on Hulu and Netflix, you probably thought Dads was funny)--but in the early '90s, that show introduced the idea of skipping the opening theme, and it led to everyone else in sitcomland following suit. It screwed you blue!