I gather that most of us older riders started out with smaller bikes and worked our way up. I learned on a 64 305 Superhawk. Rode a lot of small bikes also. The only bike I felt uncomfortable on was my cousins H-D Ultra-Glide (And no, not cause it's a H-D, I also owned a XLH Sportster and a FXE Superglide), just too bulky. The crazy stuff shown on TV, showing wheelies, stoppies etc, I think also has a effect. Wife and I went a couple of years ago to the dragstrip. They had these crotch rocket stunt riders there. Doing all kinds of crazy stuff. When it was over they just dumped the bikes on their sides and walked away, like you would drop trash on the ground. The younger people went nuts, the older people looked at them like they were nuts.
My daughters ex-neighbor rode a crotch rocket like a fool. Used to see him going down a major highway doing wheelies at 45mph in traffic. He managed to crash in Detroit at the I-75 and I-94 interchange doing the same stunt only at 70mph. He managed to survive only with a broken arm. I have no sympathy for guys like that.