http://bugzilla.mozilla.org/show_bug.cgi?id=252546
The checkin comment for this bug is "don't import IE homepage since we'll be providing our own one soon". I can understand why they'd not want to import the IE homepage if it's the default (MSN) one but if a user has decided to change their homepage then there's a decent chance they wanted it to be that way.
Reasons against the change:
1) It's only an option to import IE settings it's not forced on the user - therefore if the user chooses their settings to be imported they'll wonder why they're not
2) ISPs have a reason to not recommend users download firefox (as in off mozilla.org - not any customised version they may provide) - if a user downloads firefox then they lose the page their ISP sets for them (so the ISP would lose ad revenue and would be less likely to recommend firefox for that)
Reasons for the change:
1) A user may have had their homepage in IE set to something bad via some malware - the user may be glad to have a sane default
2) Because of (1) a user may think Firefox is vulnerable to spyware like ie is.
