Evelyn, the best kind of feedback is the kind you don't want to hear. I've griped about the same thing in the past. Unless there are extenuating physical circumstances a sensei should take care of themselves. Your point is very valid. If you choose to work in a donut shop being heavy is fine but if you choose to teach Aikido some physical discipline is in order.
Secondly, don't be afraid to offend someone. One of the worst things that happens in a hierarchical system is that the new voices (don't know if you are new) are never heard or given much less weight. Yet, they are the single most important resource that the Aikido community can learn from.