Laurent,
Although I may be the host of this forum, it has always been my aim to let the community decide what it does and does not like. It happens to be that our community generally doesn't repond well to 'what if' questions. Most likely because they tend to lead nowhere and are seldom informative.
Personally I tend to ignore most of them, but sometimes even a 'what if' thread can be interesting for its originality, quality or information. There is no reason to ban 'what if' questions. Any normal person would catch on to the forum response soon enough and adapt accordingly.
At one point you may start doubting the sincerity behind these questions. Sometimes your senses warn you with the first post and sometimes it takes time to see a pattern, but there are people who take great satisfaction in wasting other people's time or creating trouble on a forum.
http://forum.12oclockhigh.net/showthread.php?t=1477
Any forum dealing with Luftwaffe (or warfare in general) will always attract people who disagree with our choice of interest, you should always keep that in mind.