Good for the client
- Cost
As client you get more for your buck. With plenty of ready made plugins ready to be popped in at minimal cost, why would you pay to get these things especially built for you? It's also likely that clients can cut down on training costs by employing content editors who already know their system. - Choice
If I'm going to buy shampoo, ideally I want a carefully selected range suiting all possible hair needs from frizzy, silky smooth to super duppa 80s go go volume. I don't want to wait for somebody to mix up my own special shampoo or indeed pay for it. I need the money for the conditioner too. - No tie in
Best of all the clients are not tied in. There are loads of agencies using the same CMSs. A client can keep using the same agency because they are good not because they are locked into using their bespoke system.
Good for the agency
- Cost
Think of a open source/off the shelf system as your P.A. doing all the jobs you don't want to. Because you have a library of ready made plugins to choose from for all the "normal" tasks, you have time to actually put some of those more exciting innovative ideas into action. Hopefully that means clients will come back for more too. - Support
Whether you are using an open source system or a "paid for" system, you get a support network. You no longer just have to rely on your internal staff for the answer, again giving them more time to think up "new stuff". It also means you can employ people who will instantly know the systems you are using - great when you have that big job to be finished and your head honcho developer has just caught the flu. - Your client isn't tied in
Yes, this is a good thing. It challenges you to keep a closer eye on the competition and push yourselves to give the best client service possible.