What you describe is a ROMpler or a sampler with a weighted or adjustable action controller, something that has been available for over 20 years. If you want all in one there are Ensoniqs, Kurzweils and piles of other stuff at every price point new and used.. It seems to me that you have an eye on one of those latter paradigm digital recreations branded 'Mellotron' . It's ok, you don't need to seek our approval or disapproval, in actuality because of the deep technical experience on this list, you are not going to get a clean yes on function, value or practicalty.
In certain circles at certain times, music and it's acoutrements are fashion. Though distateful to me, there is nothing outside of personal asthetics wrong with it unless I am paying the bills.
So do what you want,