Right, but if you do that math, it turns out that the -5/+10 is really good most of the time. And since it comes attached to a bunch of other really strong benefits, the Feats that grant it are pretty much no-brainers if you’re looking to optimize damage output. Which is presumably part of why the -5/+10 part was removed in the 1D&D UA versions.
I think I'm going to wait around until someone finds and posts the chart. I haven't seen it in a while, but my initial takeaway was that it is less than people tend to treat it as (it really comes online well when they are combined with consistent advantage and/or massively multiple to-hit adders, whose opportunity cost also need to be taken into account). Regardless to whether they are the first thing you take or whether you wait until you've maxed out your dex, we're kinda violently agreeing, they are good options (but I would place the side benefits as dominant).
As to why they were removed, I don't know what to think. Between rogues losing reaction-SAs, Boomin-Blade-SAs, getting rid of one-handed-quarterstaff-shield-PAM, and a bunch of other not-necessarily bank-breaking effects but ones that dedicated forumites know all about but casual gamers might not have caught, my takeaway is that they want to make the style of plays (and thus effectiveness thresholds, ability to balance CRs, etc.) more similar between rules minutia types and beer&pretzel players.
Even if it is the effectiveness, I think it is the perception that matters most -- if people feel like they can't do any martial build except greatsword-GWM, halberd-PAM-GWM, longbow-SS, hand crossbow-CBE-SS, and one-handed-quarterstaff/spear-shield-PAM, then they won't pick the other concepts and the game loses out in playstyle diversity.