First, I thought the Germans did stage a fairly big victory parade. Regardless, I think any RAF raid on Paris at that point would be an extremely bad idea, diplomatically. First, the general world consensus at the time was that the European war was basically over. A British attack on the capital of France, aimed at the historic heart of the city, could be seen as the desperate act of a vindictive loser against its defeated ally, not an act of defiance against the German victor. At least, the attack on the French fleet at Oran was aimed at a legitimate military objective and made some strategic sense. Also, militarily, it could be a disaster for Britain. In 1940, a daylight attack force would be composed almost entirely of obsolescent twin engined Whitleys, Blenheims, and possibly Wellingtons, operating in relatively small formations. Based on previous experience, they might be decimated by the Luftwaffe.