Because some stupid advertisers hammered "everything but integrated memory controller ****s" into the customers brains - and this means, that differend performance segments cannot be addressed by different chipsets/motherboards in the future, but have to include diffent CPUs and different interconnection as well.
btw:
The news, you are commenting, is stone old. "LGA 1155" was, as "LGA 1160", "1060", "1066", "750", "1166" (and probably some others) a false rumor created by some people, who just wouldn't let "you got no damn clue, so shut up" come into their way.
Only LGA1156 and LGA1366 are in the market now - an actually that's not realy more, then with the core2 plattform, as LGA1366 serves the workstation/dual-CPU-server-market as well, that up to now had it's own (LGA771) socket. So Intel just shifted the border between their consumer and there workstation socket, so that now enthusiast/high-end gaming-machines share their plattform with high-end workstations (instead off lowest-end-200$-computers. somehow, this doesn't seem to be completely illogical)

too many sockets, why did intel abandon the great 1 socket system they had with 775?

Now we are going to have a headache of motherboards and cpu's.... dont like it at all.