Why the 1% crit chance for level 1?
Statistically, it's awful. An AD Mark gives 1 AD while the crit mark gives 1% crit. This crit mark is meant for laning phase, and for a lot of the laning phase, you'll have less than 100 AD (the requirement to make it equally as efficient as the 1 AD mark). Yes, if you get lucky, you might get a kill, but statistically, that luck won't come around often enough to make it worth while. Plus, the 1% crit chance rune won't do anything late game, espec when everyone and their mother is maxing crit chance, or getting p close to it.
So, why do you go for the 1 in 100 chance that you'll crit?
Edit: why downvote? It's a discussion... I'm saying statistics and giving my opinion then leaving it open for discussion... theres literally 0 need to downvote.