Pinyin's existence is as a stepping stone, and misses out on a lot of interplay between words. Pinyin negates how you can separate Chinese characters into different symbols, such as the Chinese character '鮮' ('xiān' in pinyin), is the combination of '魚' ('yú') and '羊' ('yáng'). It's certainly not impossible to learn Chinese through pinyin, but it would be an odd choice.
Pinyin doesn't negate Chinese characters. It's just tackling another issue - sounds and tones.
It's not an odd choice. I've never heard of anyone learning Chinese as a second language who doesn't use pinyin at least for the first few years.
I'm not convinced that there are enough hanzi that decompose nicely like that to make up for all the other issues.