Ball bearing turbos also have less rotational resistance than their sleeve-bearing counterparts. Which, in turn, allows the turbo to spool up faster and have a better transient response than a sleeve-bearing turbo.
About the longevity of the ball bearing turbo. In perfect operating conditions, you're completely correct. But, a ball bearing turbo is much, much more sensitive to little debris in the oil being run through the CHRA. Many people will run an additional oil filter in the turbo oil-feed line. Also (not a down side), you must run low pressure oil to a ball bearing turbo, whereas a sleeve-bearing turbo requires high pressure oil (like the crankshaft, rods, camshaft, etc). So, if you're upgrading an existing turbo setup from a sleeve-bearing turbo to a ball-bearing turbo, you need to be aware of that difference.
Build 'em Light and Wind 'em Tight.