Vendor Lock-In or One Stop Shop
I was recently discussing load balancers with someone. I said I was much happier with F5 than I was with Cisco and he countered that although he preferred F5 head to head, going with Cisco for all the network was better for them in the long run.
The situation with storage is similar. EMC makes a great SAN but a pretty bad NAS. Is it worth getting EMC's NAS for the One Stop Shop factor?