Photoshop isn't supposed to be straight-forward: it's the Swiss Army knife of art programs, if a Swiss Army knife had a gun, a shield, several bandages, and a nuclear warhead on its attachments. Photoshop is with few exceptions (pixel art being the only prominent one) the best tool for anything involving a picture on a computer, and while I admit it's a bulky piece of code, it pretty much has to be to be capable of all that it is.
As a web designer, if you've found everything you used on PS, on PSP, then PSP is definitely the right tool for you, because PS is way more than you'll ever need.