If you have the skills and can pay the bills, here are two other reasons to 10 box in Cataclysm:

Guild Raids & Dungeons Achievements
In general we require 80% of the group to be comprised of guild members. There are exceptions to this case though like 40 man raids and arenas. All the gritty details below are below.
4/5 - dungeons
8/10 - 10 player raid, 10 player BG
20/25 - 25 player raid, 25 player BG
10/40 - 40 player raid
12/15 - 15 player BG


So getting Guild Achievments should be quite doable. The other option is having a multiboxing friendly Guild with multiple sets of boxers.

The patches are getting heaps bigger so perhaps closer to release?