Well, to be honest I kinda agree, that most of the 2nd forms of 3 staged Pokemon are not only not good to exp, but that it is just pain in the ass to do it.
New of them still seems kinda increased comparing to the old ones, f.e Pignite or Dewott comparing with Charmeleon or Wartortle.
Still, now, as we have most of High Lvls in game, it is pretty hard to see someone exp Wartortle or Croconaw to get the last evolution, since it is not worth to bother for so long to do it.
I agree with statement that they could get some more (2, maybe 3 at all) weak AoE moves, like Flame Burst for Fire, Tsunami/Whirlpool for Waters etc. I think that it wouldn't make them as great as the last forms, since they'll still have lack of dmg
comparing to the same move from the final form, but will be possible to exp, so then it would have sense to catch 2nd form and lvl it to the Final, instead of hardly trying to catch the Last Form.