mixture mentioned:
"before it uses disk space (server or your desktop) and before you have to waste bandwidth and processing cycles "
Back to 1983. Again? :-)
Last time I looked, above mentioned resources were ludicrously cheap except for bandwidth which possibly is only cheap. For most home users these are irrelevant. Convenience trumps all.
Corporates may be significantly different, not sure, not been there for a bit. The difference is that corporates tend to have mirrored drives, sophisticated backups, redundant power and all that good stuff which puts up the cost of the resources substantially.
Anyway, I use free email, their spam filtering is good enough for me, so I don't care about any of that:-)