I'm not saying everything has to be boring and same everywhere, I'd like to see the world that's actually quite the opposite, that's diverse and where people are pushing the boundaries of expression. Where I see infantilisation happening is where things with very low information ratio (and usually something evoking one of the basic emotions with high valence and high arousal) are described as fun and cool.
I think OP's product is sitting somewhere on that border, but their marketing angle is definitely pushing it towards the infantility. Just look at the title of this very post, but I guess it worked, in the end we've all clicked on the comments and are here.. :)
I really dug this Reslash concept after seeing that grainy image of a classroom used as a background. It's something you just slap on because you're about to teach, but it isn't a painfully constructed "Knowledge Session" with a stock image-riddled Powerpoint deck.
Personally, I think it's been downhill since someone decided we needed ui/ux designers instead of sleep deprived developers who assumed it was always the (l)users fault for not being able to figure out how to use things. Sure, it has made things easier to use for the masses, but I don't care about the masses.
The "masses" are real people too, with feelings. We should care about them. Also, they include our family and, hopefully, friends.
But yeah, I know it's basically a necessity now, and I understand that services need to cater to as many people as possible. I just wanted to be a cranky old nerd for a bit :-)
With that said, I do agree with GP with regards to things outside of the web: products have a lot more franchise placements (e.g. disney-themed shampoos), and school for my kids have a lot more of an artsy/hippie feel than I remember my dry seats-facing-forward education some 30 years ago. Gaming among adults is far more socially accepted than 30 years ago - you wouldn't even bat an eyelid at an old lady playing candy crush in the bus these days. Etc.
I suspect an increase in middle class disposable income might have something to do with this. Look, for example, at how culture progressed over the decades in Japan. Nowadays, you have grown adults who are into moe[0] stuff, along all sort of "infantile" subcultures (by western standards).
Then sometime in the mid 2000s everything online became sanitized and corporate.