Why the complaints about lack of support?

The older symbian phone users must have been *****ing last month..."Great - just bought my Nxx and now Nokia bring out N900 and Maemo...won't be seeing any updates for my phone now"
Then today - "Oh free Maps - maybe Nokia does love its old customers still..."

On the N900 front - we've had two firmware updates already this month. How can that be lack of support?

The N900 has been marketed primarily towards developers rather than normal consumers. I wouldn't expect all the same things as standard consumers would get. Although to be honest I'd be surprised if we don't see Maps on the N900 soon.