...they're just conditioned to.
People don't go to a desk when showing up at a friend's house. They don't go to a desk when going to nice B&B or small inn. For some reason, as hotels grew larger, (and needed to find some staff efficiencies), we made people "check-in" at a desk. It's far easier to have people stand in line and come to us than to create a dynamic system to welcome guests and escort them to their room, the bar or restaurant. It's easier to get people to conform to an operation that saves money, than to figure out a new way to give them what they want in an efficient way. It doesn't need to be formal, scripted or overdone...it just needs to be genuine.
For the past six months, I've been involved in the overhaul and recreation of a new welcome for a mid-size property with 100 years of front desk history behind it. Some said it couldn't be done...they were wrong. Still work to be done, but the first impressions have been beyond favorable.
Don't get bogged down in improving old systems just because they seemed to have worked. Instead, begin with the experience every guest should have and build your operation around that.