Not entirely true, the temperature range on an e46 ranges from about 90 to around 110, my 318 used to run at 108I think you've been reading too much on e46fanatics.com. Guys there got more time and money than common sense. One member replaced the whole cooling system for 'preventative maintenance', only to have several leaks and now maybe the engines damaged - more like destructive maintenance!
Best to look, listen and feel for any problems with your car.
For cooling system you could change to lower pressure cap tho I haven't bothered but check OBC hidden menus coolant temp stays below 100 should be working ok
Coolant is well overdue for a chance, 30,000km and 3.5 years, brake fluid is only 13,000km and