If you're an experienced developer and are developing a complex project, it's much more efficient to use an IDE (Integrated Development Environment) to do all of that. You are absolutely correct. And if you're still a novice (as I consider myself to be regarding embedded µ-controllers), you can gain a lot by using FLIP (look it up yourself because I've forgotten what it means) and being able to see all of those SFRs (Special Function Registers) organized for quick and efficient perusal. But if you're trying to connect your first AT89C51Rx2 to a computer and load your first program into it, I think it is MOST instructional and well worth the effort to do all of these things as close to the lead frame as you can. It simply gives you a better and more complete understanding of what you're doing now and into the future.

Anyway, that's my two cents worth. :)