I have no idea what your guys' problem with the online is. I think it's a HUGE improvement over Wii U, and I say that having put a metric ton of hours into Wii U's online.
First of all: quickplay fixes the issue of segregating the playerbase online. Ever go into a lobby, but only 1 or 2 others join, they wait like 10 seconds, then someone leaves, and then another arrives, and it just repeats because people keep leaving and re-entering trying to find a full lobby? Super annoying btw. Plus, you'd never know how many people are playing For Fun vs For Glory or Team Battle vs solo so if you weren't finding people to play with you'd have to maybe jump around in other modes and see if people were there. At which point, you're basically already doing what Quickplay is doing. It prioritizes your preferences, but if that can't be done, next best thing is to just play Smash, not wait around NOT playing Smash. Besides, it's fun to mix things up in my opinion.
And the GSP ensures that no matter what kind of rules are being used online, you'll be paired with people of similar skill, so it can still be competitive.
And then, if you REALLY only want to play a certain way online, you can just make a public lobby and let people join you. The types of rules that can now be used online are way more than we had before, and we can even freaking use Mii fighters! Finally!
I think the online is a vast improvement due to streamlining the whole process and reducing the number of menus to slog through while still providing objectively more options than we've ever had before in online play. It's a success.