Most ARE uptight, not all are unpleasant...
They're used to rules and schedules and having to follow them. (Some complicated schedules I have to deal with include: signing up to use the laundry room (shared with 7 other families--still better than it used to be when most people were assigned a time--this still does happen some places); my children's school schedule (getting better also, when my now-10yo was in first grade she had a different start and end time (including different lunch hours) every day of the week--now she has two start times and one end time, and only two afternoons off); recycling days, etc. I have the commuter train schedule memorized, that's pretty standard here.) Rules can include enforced quiet times (there's a park near me that closes for lunch; some apartment buildings don't allow flushing after 10pm) and days off (very few shops and relatively few restaurants are open on Sunday), etc.
Anyway, I'm not sure if the unpleasantness comes from the stress of having to follow these rules or from an annoyance when other people don't. There are fines for everything from parking in front of your own building (those spots are for visitors, you have your own spot) to throwing a carton in the public trash cans (cardboard is recyclable).
Source(s):
Living here, and a very insightful book called "Beyond Chocolate: Understanding Swiss Culture" by Margaret Oertig-Davidson