-- Having less and lighter equipment makes it possible to get out of work at 5 and decide to go on a spur of the moment overnight trip. I can go home, change, pack my small amount of gear, drive to a trailhead, and hike to a campsite 3 miles away before sunset.
-- Short mile days go faster, leaving me more time for views, bird watching, exploration, and hanging out at the campsite.
-- Long mile days are actually possible. I'm training to do a 116 mile hike in three days. I would never have even thought that possible without having gone ultralight.
-- I only started making the shift toward ultralight a little over a year ago. I've done more trips in that year than in the previous five years combined. It's just way more fun when you're comfortable.
All of this said, there are some luxuries that I like taking. I'm trying out tablets right now for purifying my water, and not convinced that I like them better than a filter. I may go back to the filter for low to moderate intensity trips. For high mileage days, though, that extra 10 oz makes a big difference.
I like bringing my Tarptent and haven't made the switch to tarps yet. I plan to use one for that aforementioned 116 mile hike, but bug netting is a luxury that I'd rather not give up in New England.
I've brought my 21 oz insulated, inflatable sleeping pad on more trips than not. Sure, it's heavy, but that comfort makes for a great night's sleep. This pad only stays home on high intensity trips where I'd rather not lug the extra pound for 20-25 miles per day. I don't do that many of those.
Here's the thing, though: With all of those items, my baseweight is still around 11-12 lbs when I go solo. When I go with my wife, it's more like 8 or 9!
If for some reason I want to bring extra photography equipment, fishing equipment, wine, or a six pack of beer (cans), it's no problem. My back will still feel good at the end of the day. Works for me!