I think the main reason people recommend the 50/1.8 for new Canon DSLR users is not totally down to the "normal" length of this lens but mostly down to the price. It's so cheap that it's basically a steal, and at that is a nice way to get used to a prime lens and the advantages (and disadvantages) that those bring.
If the Sigma 30/1.4 was $80 everyone might recommend that. Or if Canon had a reasonably priced 30 or 35mm prime in the f1.8-f2.8 range that was USM then perhaps people would recommend that. But as it stands none of these things are true.
I personally find myself using the 35 f/1.4 L a lot more often that the 50 f/1.4, but I'd have never considered paying all that money for the 35 if I had not bought the much cheaper 50 first.
If the Sigma 30/1.4 was $80 everyone might recommend that. Or if Canon had a reasonably priced 30 or 35mm prime in the f1.8-f2.8 range that was USM then perhaps people would recommend that. But as it stands none of these things are true.
I personally find myself using the 35 f/1.4 L a lot more often that the 50 f/1.4, but I'd have never considered paying all that money for the 35 if I had not bought the much cheaper 50 first.