George Walker Bush famously become "Le buisson marcheur de George" that is "George's walking bush" thanks to an extremely stpid autocorrect software (bangs head against a wall)
Are Dassault's engineer's getting too conservative in designing new fighters and sticking to what they already know?
this is a little silly. "If it works, don't change it". Dassault has a long standing tradition like this. It worked pretty well for the company since 1949 and the first Ouragan. In fact all 5000 combat jets they build can be linked to each others, all the way from Ouragan to Rafale, including Mirage, Mystère, and Etendard. By 1956 the SMB-2, Mirage III-01 and Etendard IV-A were the same basic fuselage, only with different wings or air intakes. The rear fuselage with the Atar inside was essentially the same.
So yes, they are conservative, but for good reasons