Right, but critics also view these movies with a very different perspective than most of the regular adults that see them - most of the normal adult audience for kids movies (other than perhaps Disney and Pixar movies, which have an adult following) is parents, who are likely to be annoyed by them (or find them bland and inoffensive at best), especially if their kids want to watch them repeatedly.
If you're really into movies as I am, it can be very interesting to watch one of these kids movies that you'd normally dismiss entirely without a second thought but which critics rate highly. Compare them to true classics of the genre - often the newer ones are more complex, have better stories and scripts, surprisingly deep themes, better acting, everything. Many of the older children's films do have those things too (e.g. the original Willy Wonka film, where the remake is the one lacking those things) but most are pretty bad.
Anyway the point is, by the metrics that critics rate films by, these are legitimately good films and aren't actually "bland but inoffensive". Those that are are rated accordingly (and really, most kids movies definitely still fall in that category). You're not really missing out if you don't see them, but they'd be worth paying closer attention to if you had to watch something with a kid.
I think the data bears this out really well. Dumb adults rate extremely dumb adult movies highly while dismissing potentially-actually-good kid's films without giving them a fair chance. I don't mean to actually harshly judge anyone who rates those dumb movies highly, because a couple of them are things I enjoyed, but they are downright bad regardless