I thought long and hard about the poll and without looking what the rest of you had voted I finally decided no! The reason for this is:
As you all have stated it should be obvious that being an good uke helps your training in the long run (you give better training to more nage who in turn give it back to you etc.), but
have you never trained with an aikidoka that had wonderful ukemi, the best, but then turned out to not follow it up with remotely the same skills as tori. That goes both way. There are them that can throw you like a glove but can't take a decent brakefall from shihonage. I don't want to step on anyones toes, but this is my excperience. Since the Q in the poll was given(my interpretation) the correlation between being able to fly and being able to send someone flying I have to say no. However! It turns out that the really good sensei's out there all performe (or have been performing) marvelous ukemi, because in the long run it helped them train well enough to develop skills that they all are famous for today.
This is without saying MHO!