Well, let me put some questions to you. What happens when a job spans more than one financial year? eg a wedding where you shoot the dress fitting in one year and the event months later. Or do client companies never merge, or families never split? Think of your local supermarket - does it run separate inventory records for each store or for each type of product? Of course not - they use store and product codes, ie metadata, so they keep control of everything in one place and can see their total vegetable sales year by year without loading one catalogue, then the other etc. Turning back to LR, why the urge to break up control of your picture collection and workflow? Wouldn't you save time if you could just copy the keywords you applied to the 2014 medieval house shoot for client A to the similar scene you're just shot for client B, and how much time will you save next year when prospective client C wants to see samples of your best medieval house work and you can just double click the "medieval house" keyword and see everything you've done? Of course, you could always open the FY 2014 catalogue, and then the other annual catalogues one by one, or just try to remember which client catalogues to open. Then the client says only show me the wide angle or interior shots.
C1 was mainly a raw converter, and that's how you've been using it with sessions, but LR is a raw converter and a cataloguing tool. Sessions and the catalogue are very different animals. While you can break up control of your workflow and picture collection, if you want, you wouldn't be squeezing the most out of LR.
In practice, other catalogues may be needed. There's the example of needing to roundtrip a shoot, or you might have a business reason to start a job in a new catalogue. For instance, it would be nasty if a wedding photographer somehow mixed up pictures from different events, so it's quite common for those LR users to start a new catalogue for each engagement, archive it when the job's closed, and then use Import from Another Catalog to bring the shoot into the catalogue that controls all their work. I maintain a separate catalogue for photos by some other photographers, or I know someone who has a sideline shooting male nudes and keeps them in a separate catalogue from the single catalogue for her event and portraiture business. So there's got to be common sense and flexibility too.