OT: At the beginning I thought like you. Every tool had to be easy to use to achieve things I needed for my games. Now, I prefer good tools that take me a week or two to gain some skill. But with this skill I am able to achieve better results that I'd ever dreamed of in my "I want an easy tool"-days
Yea, you'll probably find that eventually it's a lot better just to learn how to use industry standard software instead of wasting time with quick-fix software like MSPaint. Don't get me wrong, they're good for fixing the odd pixel or resizing, but I wouldn't do much more with it.
A good, low price software I use is Corel Paint Shop Pro. It is similar to Photoshop but it is a little more user-friendly. They have sales which means you can get the software for a low price. It is good for designing both simple and complex graphics. Only downside to it is that there are not as many tutorials for it as Adobe Photoshop.