I'm not a Uro, but I am a doctor. And I hate to "out" colleagues, but much of it is in them following the money. Imaging is cheap, and insurances don't pay much, especially for how time consuming it can be to set it up, have images taken, and then read and interpreted, and then relay info to the patient. I'm not condoning it, instead am condemning it and have been very vocal in my state board.
There's not much money in Peyronies Disease for a uro, unless he's doing an eventual implant, which most of them aren't even trained or qualified to do. But in bladder stuff there's big money, and those problems apply to a larger demographic (men and women) than Peyronies Disease does. So it is tough to find someone who's going to give you adequate time and attention for Peyronies Disease unless he truly specializes in it and has enough cases to build a practice around it.
BUT - you can and should insist on imaging if you think it's right for you. Absolutely. And note that any doctor can order imaging of any body part. If your uro won't, but your GP is a good guy and you have a good relationship with him, ask him to. It doesn't cost him anything at all to send you to an imaging center (he won't have US or MRI in his clinic likely), he just needs to write the order. I literally do it all the time, even for body parts I don't plan on treating.
And they're often much cheaper without insurance than they are with. I can order a cash MRI here (Arizona) for $275, where the insurance cost and even the patient portion after insurance, often exceeds $1000. So even if your insurance won't cover it, you can go in on cash pay and get it done. But it has to be ordered by a doctor.
Hope that helps.