I don't think that IT departments fail to see the vendor lock-in of MS, rather that they want
and embrace such lock-in. Many IT professionals have spent their careers getting various MS
certifications, are in a comfort zone, have tied their personal fortune to MS, and are loathe
to learn anything else. Since company management defers to their "judgment", IT staff is able
to put the pieces in place that will guarantee their long-term employment in their comfort
zone.
In a lot of cases, I think it's as simple as the above scenario as to why obviously inferior
MS products gain significant market share. Above all, politics rule the day in the Enterprise
Data Center.