if it comes with loads of good, crafted, inspiring presets so I can make music and find something inspiring straight away, it's value to me is higher. For my music, I don't generally start with a raw sawtooth and tweak - my process comes from playing.
So, while I enjoy making sounds from time to time, my main utility for a synth is to provide me with sounds to help me create music. If i have to make all my sounds before I can begin, then it's not aiding me in the process.
I do think though that you get much more out of a synth if you can learn it and make your own patches, providing you are skilled enough at it to make usable ones! It's like finding your voice - an instrument becomes more personal and more rewarding that way. So I do sit down outside of making music to make sounds - virtually always from scratch, so that I have some new ones for future sessions. And gradually you build up your own library that way. 100% loaded with sounds you like.
So, if a synth comes with weak presets, or ones that are not suited to my taste, then I will feel I am getting less value for money. Definitely. And it therefore influences any purchase decisions.
I feel that the strongest instrument developers at the moment have excellent instrument design skills *and* excellent sound design skills. But I'm not going to talk about Spectrasonics, they get enough love from me elsewhere
You just have to look at the effort that the larger companies like RolaKorgamaha take into voicing their instruments to know that they consider presets *vital* to an instruments success (slightly different market I know, but the principle is the same).

