...and partly to experimant with some new ideas about the game mechanics in general.
Nothing is even near Modding in that case, believe me - i tried searching through hundreds of info threads here & the essential was IN the gameplay as much as with the trial&error process of modding.
Paint'ing, omg... there are sooooo many good free alternatives on numerous specialized sites that it's really worth "testing" a few (Gimp is great, PSPro better, PhotoShop too costly for the casual graphics enthousiast!) progs if only to figure out what you'd be comfortable with -- but, i'd highly recommend sticking with it in the long run if only to ease the expectable learning curve for UI controls, features, options, plugins, etc.
Say, i didn't like what Corel did with PSPro but i've been familiar with old Jasc versions - and, creativity wise Gimp can certainly feel like paradise to some.
(PS... as for being able to receive "free" copies of an earlier purchase when upgrades are done -- sadly, that's the usual (but unfair, btw) trap of products growth from corporation that milk us all to death for profits. One specific stuff, i'd like done once and for all about these business principles is the darn AV_Security issues - re-re-re-renting a program through multiple ongoing Licenses yearly or less is a VERY deep loophole of an exploitation of users. Specifically in the case of extremely solid Virus protection (bought once at regular price!), it's in the best interest of evwwweryone on the web forever; if the internet stands any chance against Piracy, Criminality, RootKits, Trojan, etc.)