Interesting thread - i didn't realize it was so old and was surprised not to hear some familiar voices chiming in with their hair on end for various points being made. Now i realize why!
I reduce cream for a really simple steak sauce (simmer cream till it's thick and then add mustard and chopped parsley) - my very generous, then-vegetarian son-in-law, knowing how much i like meat, bought me this book by John Torode on beef and it had this recipe - i turn to it all the time when i have a nice steak and want something special with it, but don't have time to make any of the more elaborate sauces.
The italian thick cream tastes awful - it's the mainstay of many a family to feed kids quickly and easily and know they'll eat it - boil some packaged tortellini and pour the cream on them from the UHT package and put some grated cheese, but i can taste the UHT taste (UHT=ultra high temperature - you can buy milk like this and keep it out of the fridge before opening for several months, same for cream).
I also reduce cream for certain dishes i got from British recipes, where the cream is sooo dreamy and thick already you have to spoon it! Simple things like blanched spinach and celeriac cooked in the oven with double cream. I have to reduce it here.
I would NEVER put any starch in it. I'd be able to taste it. And roux - forget it, it tastes like bechamel, which is fine, but a totally different thing. No way. Cream has a freshness that gets ruined, i think, if put with thickeners.
And let's not get into fettuccine alfredo with all the concoctions it's become associated with.