Why would disable? If these things could really add up that better user experience rather than on having that standstill.
Pretty sure this would really be that pertains about stuttering due to animation? I have noticed this one too but
it isnt really that much a bothersome but rather its really that giving that more engagement towards on what you are doing.
Well, this isn't bothering you does not really mean others are bothering about it. You can share your point of view while others can also do the same. Right? So, this is not a good question when you ask why would disable it. As you can see, Quidat said that he is using a good specced PC and still it's it stutters. You cannot really be able to imagine how it will work on low-end computers unless you are one of the users.
A lot of casinos already have enable/disable animation features and I am sure you are not going to ask them why they implemented such a feature because it is working fine for you and that does not bother you.