I agree; everyone you train with teaches you something new. Our dojo has a everyone-helps-everyone-else kind of policy, beginner or not. We all give each other feedback and advice. Thankfully, however, I just found out that this student is having trouble at college and is frustrated that he can't throw me. I'm just glad I know what's bothering him.
Okay, let me be blunt and that that I think one thing you appear to be missing is that there are multiple reasons why someone might not be able to throw you. Many of which are really more about piss-poor ukemi by a newbie student that no one wants to hurt. I've had newer students that I didn't finish throws on simply because they were too open, too vulnerable, and too busy fighting off what they thought was going on. When in fact a quick atemi to the face and a rousing throw that they wouldn't be able to handle was what was really called for. Or any number of other things that they likely wouldn't have been able to handle. So you smile, try again, and leave it to sensei to fix. If sensei doesn't, however, keep in mind that in my experience eventually someone will deliver that lesson whether you're ready or not.
Best of luck to you.