If someone didn't want to be limited to these size restrictions, they could write ?width=###&height=### in the url, but then comes the annoyance of every person that wanted to properly view that program having to copy and paste that into the URL and reload the page.
I would find this awesome, and I'm sure so many others would, if the width and height options were text fields, where the creator just typed in a number of their choice, rather than just being limited to 100px increments all within a small range. I'm sure that graphic artists would like this, because when they recreate an image what has seemingly arbitrary dimensions, such as 577px by 432 px, it would be really nice to just be able to set the dimensions accordingly.
I don't work with HTML projects much, but I do notice that the canvas size there has similar restrictions.
Any thoughts on this from anyone?