Yes, Lazarus uses the system font, but try the fact of using a modern PC with screen reso of 1920*1080 for a while then revert to use old resolution of 1366*768 or other. You will feel unconfortable when working.
I have to hack the IDE font to do that, but it will be better to have a page on the tool ==> option that permit to change , IDE font/size & FormDesigner font & size.
Thanks.