I'd say there are two distinct issues:
The issue with the poppy itself isn't so much glorifying war as nationalism. It's very much a British (and, to a lesser extent, wider Anglophone Commonwealth) symbol, not an international one. Which is fine - plenty of countries have their own special ceremonies and symbolism for remembrance of war dead - but it also means wearing one is in part an expression of patriotic attachment that many don't share, so don't expect them to wear one.
The issue with glorifying war is not, in my opinion, directly to do with the poppy, but more to do with how remembrance ceremonies are phrased. There'll always be lines like "they died for our freedom" or something like that. No, not all of them did. Some of them, maybe. But some also died for no real reason, and some died for the wrong reasons. Pretending that all soldiers who die have done so in the service of good motives and results is very much glorifying war.