I would tend to agree with you that 1800 objects are a LOT of scanning objects. That said, some systems have talk groups defined for every little thing you can imagine. The helper to the first assistant dog catcher in the northeast portion of sector ten has his own talk group. That kind of thing. Most people aren't going to care about monitoring these talk groups, but the wildcard object works better at finding truly new talk groups if you have all the known talk groups programmed (even if not assigned to a scan list).
I'm in a medium-sized metro area and have about 600 objects programmed. I have most of the talk groups for the city and county public safety systems programmed, but I've only had the scanner a few weeks and still have more groups to discover. At this point I'd guess I'll end up with 1000 or so objects. I can see how 1800 might seem like too few if you live in a big city and want to have everything in the city, county, and surrounding areas all programmed at once. In practical terms, with a bit of planning, I don't think it will be much of a limitation for the vast majority of people. No matter how many frequencies or objects you allow, somebody is going to find a way to claim it's too few.