Honestly, I can see the logic behind rotating out older attractions in favour of new ones. Just from an engineering standpoint it's going to get increasingly difficult to maintain older machinery until you get to the point where you either have to do a full top to bottom renovation, or just pull the whole thing, at which point I'd imagine it comes down to a cost/benefit decision. Plus in terms of brand recognition, the primary demographic (ie: children) are going to be more attracted to what they know; the more recent and popular movie properties. Long time visitors may have a lot of affection for mascots and characters that have been exclusively at the park forever, but an 8 year old visiting for the first time is going to more drawn to a 'Frozen', 'Dory' or 'Moana' attraction. Which by of course supports the merchandise sales, which is of course where the real money is.
On top of that, there's an upper limit to the amount of space they have in the parks (and how much ground they can reasonably expect an average visitor to cover per visit) so in order to put in something new, something old has to go, and you need new things to keep attracting repeat visitors. What constitutes "classic and untouchable" old and "outdated a replaceable" old is no doubt a hotly debated topic among fans which I am in no way informed enough to have an intelligent opinion.
Honestly this kind of things feels like fairly tame compared to some of the other complaints I've heard levied at Chapek, not least of which being a supposed rather militant aversion to unionisation, actually paying his employees a reasonable wage and generally willing to cut corners to get as much foot traffic for that absolute least cost possible.
