But the cost is that you will burn out quicker than if you stuck to the program. Right now it feels fine because you're not yet lifting heavy enough, but with more weight you will hit a wall very, very fast.
It'sI don't mean to criticize. I did the same thing in your shoes. But we all need to realize that it's a little strange for someone who is just picking up a barbell to make dramatic changes to a well-worn program. I understand the mentality. Again, I did it too. (I'm pretty sureI'd bet that seventy five percent of people reading Starting Strength have similar thought processes.) It didn't work as well as It's just that experienced coaches and widespread programs are generally better than a total beginner's ideas. For me, I got better results when I followed the program.
Furthermore, fundamentally altering a program as a total novice for the sole reason of "enjoyment" is perhaps not the best way to achieve your goals. But I say that because I want to train, not to exercise. Rippetoe talks about this, fundamental distinction in his article on T-Nation, The Biggest Training Fallacy of All:
You have to ask yourself: are you lifting because it's fun, or to achieve a goal? Do you want to fart around in the gym, or are you there to achieve something? If you want to exercise, modify away. Do the exercises that are fun, arrange them for maximum enjoyment. But if you are training, if you are working towards a goal, if you want to get somewhere long-term by picking up the barbell, I recommend being diligent and consistent and sticking as close as possible to the program as written.