Yes, people did like MK11 Towers of Time, not only because of the unlocks but also because of the gameplay, both with the modifiers and Konsumables, a lot of which granted an attacking assist. NRS and WB clearly saw that thanks to the Race against Time data and expanded on both, that's how we got both the Kameos and Invasions. And considering that MK1 still outsells both SF6 and Tekken 8, it shows that people do like both Invasions and Kameos. Just because that you and some other people on the interent that keep screaming their negative thoughts didn't like it that doesn't mean the majority of players didn't. The data doesn't lie.
As others have mentioned, MVC games had multiple characters that needed to have an assist. I will give another example of my own, Omega Red in MVC2. Omega Red couldn't have chip the opponent in MVC2 due to his slow super moves and one-hit specials that he needed an assist to chip the opponent, unlike other characters in MVC2.
And just because you expected something and didn't get it, doesn't mean it's not a good thing. I also didn't expect MK1 to have both MK and Pokemon, my top 2 favorite video game IP's, into one gigantic mode, which is of course Invasions, but MK1 got it and I'm having a blast playing since day 1.
NRS clearly have shown that they are willing to have the idea of gameplay-based customization systems as major part of their gameplay design, both with the preset Variations (MKX), Gear system (IJ2), Kustom Variations (MK11) and now Kameos (MK1). You should've expect them to have such a thing after having that design choice for 3 games in a row to have something like this in MK1 as well. And like I said already, people do love it, both casuals, single player guys, online players and pros alike. Yes some people don't like it, but considering that MK1 is still the best selling fighting game right now, the majority of players do like it.