The installation of any "trinket" should be based on:
"Will having this feature increase sales, or not?"
If you cannot pragmatically answer this question in the affirmative, then don't bother installing the "trinket".
In my opinion, stuff like flash should ONLY be used when it enhances the customer's knowledge of a product, and supports them in making a purchase decision.
Some products benefit from a little "flash movie" that shows things like how to use it, configure it, or apply it in useful ways.
Self-assembled furniture is a good example. if I see a little movie showing me how easy it is to assemble a flat-pack bookshelf, I may be more tempted to buy it.
But having "trinkets" just for the sake of showing off to the competitor web-designer down the road is pointless, in my opinion. If a website component does not actively and measurably contribute to the sale of that product, then its inclusion is probably detrimental at worst, or superfluous at best.