While I do think the Switch is shaping up quite differently to the Wii U, it's not really accurate to pretend that the Wii U didn't receive praise and promises of support.
Gearbox in 2012 on Alien Collonial Marines (lol): "The Wii U is a powerful, powerful machine and it can do a lot of cool new things. And so the game itself, moving it over to work on the Wii U was not much of a chore."
EA in 2011: "We look forward to seeing great EA content on this innovative new platform. Nintendo's next console is truly transformational, a better platform than we've ever been offered by them before... The Wii U is certainly a platform we like and will support going forward."
Activision in 2013: "As we have said before, we're committed to doing everything we can to support the Wii U, which is why we're excited to be bringing some of the most popular entertainment franchises in the world to the platform this year"
There's other stuff out there as well, and let's not forget that the 3rd party launch lineup for the Wii U looked pretty decent when the Wii U was unveiled in 2011.
The difference is that there was also some less than flattering stuff said about the Wii U, and so far everything I've seen about the Swtich has been positive.
Fair enough, Gearbox's comments are similar, and were definitely an over-exaggeration in the end, but that's pretty much the only comment here that lends itself to your point (not taking into account how dishonest they were in general at this time).
To say that Activision, EA, Warner Bros, Ubisoft just lied directly to our faces with comments like the above is just incorrect. They supported the thing in the beginning, I should know, I bought a lot of 3rd party games in the first year. Sure they weren't perfect, but fuck, it was a new platfrom that had a vastly different architecture and
shitty tools at launch. These poor devs/pubs tried (just read that link). They legitimately put a respectable amount of 3rd party games on the Wii U in the first year, so it's not like they were completely lying. You can't expect EA to want to continue to want to give "unprecedented" support when the system has shown to be failing, is giving their developers a hard time, is under-powered in comparison to it's direct competitors, costed money to develop for, and the games weren't selling.
In the end it really is down to how Nintendo handles their own platform. With the Wii U, Nintendo created a platform that simply wasn't inviting to the type of players that would buy "core" EA, Ubisoft, Activision games. They marketed their platform to really young children and families, and expected games like Batman AC to sell well. From the way the system looked, to the marketing, it just came off as "childish". The current situation is friggin vastly different.