I wouldn't say the developers don't put heart into these games cause they do poorly, more like they know they don't have to put much effort into them because they know they will sell incredibly well regardless.

For the most part, this topic is a bit broad and there are several factors to consider when trying to find the root issues. For Disney games particularly, I blame part of the issue on their own gaming division being rather poor in quality. It's not really that important to them since the licensing of the IP can translate to money from any where and game development is a lot of effort with little reward in the grand business scheme of other children's stuff. It's the reason why the best license games tend to be ones that are outsourced to real gaming companies. Kingdom Hearts and the Capcom era of Disney games are quite the stand-outs, as are the Konami arcade license titles. Nowadays the best license titles are usually fighting games based on popular anime series or mobile titles where they strap the license onto a popular game like Sailor Drops being a Candy Crush clone with Sailor Moon attached to it.

Companies could do more with the licenses, but the sad truth is that games are the least cost-effective application of merchandising since it requires real effort to make them good, and the target audience is less likely to be as engaged with a well thought out game over a pre-existing game with wearing the mask of the IP. The only place where this isn't the case lately has been major IPs with broad appeal like comic books and Star Wars, where the IPs are handed over to major companies to make strong video game franchises and even then they'll stick you with DLC and loot box nonsense like MvsC: Infinite and Star Wars Battlefront.

So yeah, any IP whose target audience are under ten, will likely never see a decent video game adaption of the IP since the bar for satisfaction by the target audience is too low for the developers to care, while IPs that can extend to older audiences have their own issues. Like film adaptions, the real issue here is that adaptions are created for broad appeal, not to appeal to the core fan base. The fans will likely check it out regardless so no sense in appealing to them too much, so the goal is simply to get the casuals interested enough to invest in becoming a fan, so ultimately, core fans will always get a watered down experience cause they're not as important as a demographic since they are already considered a "sure thing".