I'm wondering if the problem predates 5.0. A couple of days ago, at Google's recommendation, I did a hard reset to fix a screen issue. The tech said it would load 5.0 as part of the reset, but it installed 4.4.4 instead. When I went to set up my corporate account for email, calendar and contacts, it kept asking for a certificate that I don't have and required me to set up a screen lock code, password or pattern. See the screenshot that another user posted at
Android 5.0 Lollipop Release Discussion - Pg. 592 | Google Nexus 5 | XDA Forums
My email is hosted with Office 365's Exchange Online. I'm self-employed, so I'm the account's admin, and I couldn't find anything on the Exchange end requiring those things. Thinking it might be a bug, I did a second hard reset, but same result.
After some Web searches, I found a solution: When setting up an Exchange account, don't enter your email address at the beginning. Instead, use your domain name, \ and your user name. For whatever reason, that eliminates the screen-lock and certificate barriers. But it does preserve all of the other IT security stuff that Exchange provides, such as remote lock and wipe.