Flash memory in general has a maximum number of flash reprogramming events it is designed to handle. However for consumers it's a non-issue. For folks like me who design automotive ECU hardware we re-flash lots of times for a given vehicle program, and we still don't come close to that limit (lmits vary by flash technology and supplier).
Bottom line, I don't think you have anything to worry about.
Now, if BMW puts in their code to limit reflashing, that's a different issue and they've decided to insert that limit.
2008 335i sedan | black/black | Sport | Premium