To me it seems much more logical to explain something with a phenomena (acceleration) that is not made up; even though the theory behind it may, still, just be a theory. It also perfectly explains the effect that is present, just as gravity appears to. With all the evidence I have read on this site, I believe that the earth is flat; it's not necessarily the incompetence of "gravity" which has swayed me towards becoming a FEer, it was just the first thing that made me start to doubt the consensus that the earth was round.
Acceleration isn't an alternative to gravitation. In fact acceleration can be caused by gravitation. The question is what causes our acceleration relative to earth when our feet are not on the ground? Is it because objects with mass attract each other (gravitation), or is there some mysterious force accelerating the earth (universal acceleration)? Acceleration isn't made up, but the force which causes the earth to accelerate in FET is. How is that more plausible than gravity?
It is good to be skeptical of universally accepted ideas such as a round earth, but you still have to consider all possibilities objectively. Neither theory is perfect, but you need to look at the probability for each theory to be true. The necessity of the elaborate conspiracy to make FET possible certainly gives RET the advantage. Logically, FET would need some very strong evidence to make it the more likely theory.