Why were you criticised for doing it that way? I mean I think it's crazy not to use DHCP for workstations at least, but maybe there is something specific to the environment that changes that equation.
The only issue I can see with DHCP is ensuring that your scope is properly created and doesn't cross over with the pool of static addresses you use (even that can be got around with reservations but its more work than needed).
That aside, users should never ever need to know whether or not you use DHCP because their workstation should 'just work', except for when the DHCP server is not available (and if that's an issue, you just have more than one DHCP server online).
Convict makes a good point about documentation, make sure you do have the IP address ranges documented, explaining what you've done, why and how to find it. I don't think people are comfortable with the idea that some tools are "self documenting" (and to an extent they might have a point, how would you easily re-create your DHCP database with all your reservations, if you couldn't restore from backup?).