Dude, you've literally spent this entire thread arguing that this feat sucks and that there's no good reason to choose it. For you to now say, "I think that it works exactly as intended," only flows from your previous logic if you believe Elemental Adept was intended to be a suck-trap.
"The feat does what it is designed to do: bypass a specific elemental resist." You're looking at the implementation to see its intended purpose. I think this is a mistake. I believe the name "Elemental Adept" gives us a better hint to the feat's intended purpose--making a character "adept" with a particular element--and I believe that overcoming damage resistance is just one possible avenue for accomplishing this.
"I have never met a player who wants to play [an elemental specialist] and absolutely refuses to take [spells from outside their element]," is asinine. Is the fact that you've never met such a player proof that they don't exist, or that they shouldn't exist? I believe we've established that elemental specialists are a relatively common trope in fantasy fiction, so it should be no surprise that players will want to play characters that fit that role. Ice King characters should have some options to their cold-magic more versatile than that of joe-generalist, and Elemental Adept attempts to do that but fails (as you yourself spent a bunch of math-y posts pointing out). I only want to houserule it so that it is a more palatable option for a wider range of characters.
In this thread you've vacillated between, "Elemental Adept sucks and nobody should take it," and "Elemental Adept is fine." Which one is it?
Really?
Where did I say that it is fine? I said "Mathematically, it is typically not a good choice, but it can be a good choice if the player is happy with it." meaning that it's dumb to take it, but if the player absolutely wants it and is willing to give up other better options just to plug that hole, have at it. It's not mathematically good in this case, it's emotionally good for the player since he thinks he's getting a bang for his buck. He's not, but if he is not really paying attention to the math, he can at least feel good about the feat.
But, it still sucks. A player who wants to take a theme based PC that absolutely refuses to take one elemental spell outside his own theme probably exists and they can play however they want, including taking this feat.
Please read what I actually write and not your own little spin on what I write. My stance has not changed, just your spin on it.
There are several feats (and spells and abilities) that are better in the mind of the player than they actually are in game play, but that's ok. Players do not have to be mathematically minded and drill down into the details, they just have to have fun.
And if you think that you should go to the name of feats to get a good understanding of their intent instead of looking at the details, then you and I really cannot even discuss it. Do you buy a car based on its name, or based on its features?

By the way, except for fire, there are not that many theme based spells as is anyway. After taking every single acid spell, a spell caster would still have quite a few prep slots remaining. Elemental theme based PCs are not yet well supported. So, I'm not going to worry about them and I will suggest to any of my players who want a theme and want to plug that hole with Elemental Adept that they would be better off getting a more versatile feat and using a backup damaging spell of some other type (even force damage like Magic Missile) than trying to shoehorn a PC concept into a narrow box which is not yet well supported by the game system. No concept is 100% supported by the game system, so many players adapt. At least my players do. But, adaptation does not require houserules.