So Luxottica stopped distributing Oakley's products in Sunglass Hut, etc.. which deprived Oakley of the majority of it's revenue, causing their stock to crash.
Oakley then accepted a buyout offer from Luxottica.
So to answer your question, why are there not better Luxottica competitors.. because when someone produces a good product, they'll become large enough to attract Luxottica's attention...
If Luxottica controls the distribution channel.. what options do you have if they want to play hardball? No good ones.