As someone who contributed a lot on LWN to discussions about Sun OpenOffice, who uses LO, and has their name on the developer credits, I would take strong issue in "two independent suites are likely to put a lot of effort into being the same".
I am well known and on record as hating Word, and LO/OO writer by association (as a bit of a clone). So why do I use it? Because I feel I no longer have any choice. I'm a WordPerfect fan, and if I could get a paid-for copy that would run on my system (gentoo linux) I would buy it (if I could afford it, I'm currently unemployed :-(
And unfortunately, the feature that locks me in to WordPerfect is a feature that cannot be added to LO without *massive* engineering effort. Don't say "well, learn LO/OO better, then". That feature is also a *massive* *time* *saver* for me, and more experience with Word or Writer won't help. It's the feature that lets me look at a document - ANY document whether written by me or anyone else - and lets me work out, *in* *seconds*, WHY the document is doing what it's doing. How often have you had a document with odd formatting and you've been unable to fathom out why? That just doesn't happen in WordPerfect for me.
In case you haven't guessed that feature, it's called "reveal codes". I guess I could emulate it by dissassembling a Writer document and reading the raw html ...