When manufacturers add new color options several months into a phone's run
I'm pretty glad I didn't buy a Nexus 5 at launch now, because I'd certainly be kicking myself for not having the red one.
I wish manufacturers would be more transparent about when they intend to release new color options for their models. Motorola did a good job with this with the Moto X: we didn't know exactly when the wood backs would be released, but we knew from the start that they were coming, and so the people who really wanted the wood backs knew to wait. Google, on the other hand, has been pretty bad about this with the Nexus line: white versions of the Galaxy Nexus and Nexus 4 were released several months after the black versions, and now the same deal with the red Nexus 5. Ditto Samsung, which releases new color variants for its Galaxies S throughout the year.
I'll probably be considering the Nextus in the fall, against whatever flagships Motorola, HTC, and Sony have out. But not knowing if a much more handsome color variant is the pipeline will definitely give me pause, and incline me towards the manufacturers that don't have a habit of doing this sort of thing.