I understand what you're talking about however if there's no challenge then there's no fun to be had.
WoL was far more memorable because of the difficulty, and saying that being the zerg means you can just snowball everything with ease is not a legitimate excuse to make the game boring.
You're invading the most heavily fortified terran planet in the sector and you can just mass lings and use kerrigan to deal with any tanks, without fear of losing any engagement, that's not fun at all and in WoL it is possible to wipe every single zerg base you see, INCLUDING the bases on char if you play your cards right... However Kerrigan is always the royal flush in HoTS
I looked on the SC2 forums and I'm part of the majority as many casual players (such as myself) don't even put effort into the game and win primarily because kerrigan can solo every single brutal stage by herself if micro'd half decently. She can solo 2 hybrids on brutal, that's 3k health/shield each and she can scratch by with over 50% hp, not fun.
The only missions causing people to put a slight bit of effort into are the ones where she's not available, and even then they're still too easy.
It's a damn shame too because mixing up your strategy to win, trying new unit compositions you had to do in WoL and in HoTS the idea of switching unit powerups to better cater to doing better in the upcoming mission is all obsolete and pointless.
I hope Zeratul is not playable in LoTV and no warp in exists or it will suffer the same fate.