>just like hundreds of other companies offering products with "Office" in their name

There may be hundreds of other companies selling products with the noun "office" in their names, but there only is one producing a productivity suite called simply "Office". I would expect launching another productivity suite called "Office" would be trademark infringement. Just like I can't release a car called "Beetle" or "Golf".

Microsoft never called their productivity suite "simply" office, nor have they registered a product under that name.

> productivity suite called simply "Office"

Microsoft Office.

I doubt Microsoft can own a name as generic as Simply "office".

Office.eu does not hold any resemblance to Microsoft Office in terms of logo, typography, makes no reference to MS, etc.

Of course they can sue. The most competent employees at MS are likely their lawyers and lobbyists anyway.