Lumia Icon for the big 4?

Any insight on why MS/Nokia can't do what Samsung has done for the S3, S4 and the coming S5 by having the Icon on the big 4 carriers? Also, with all the many Lumia variants running around, I thought maybe limiting the other variants to three models would make more sense from a marketing and inventory management perspective.
U.S. MARKET Lumia variants and carrier line-up
Nokia Lumia Icon: VZW, AT&T, TMO, Sprint
1020: AT&T 4G LTE, unlocked GSM via MS Store
Lumia 525: AT&T GoPhone, TMO pre-paid, MetroPCS, Straight Talk
Lumia 822: VZW Pre-paid, Boost Mobile, Virgin Mobile