Just going on record to inform Microsoft (although I'm sure they already know), that Internet Explorer 11 (in Windows 8.1 "Blue" preview) forces you into the "basic" view for Outlook Web Access.
When I first noticed this, the webmail looked so different that I wondered if somehow my O365 upgrade to Wave 15 (2013) had started without me knowing it. It turns out, no such luck. Still waiting on any communication from MSFT regarding upgrade of my Education/A2 plan.