Router plus DSL: what for?

Question

What do you need a router for if you already have a DSL router/modem? 
I have a router/modem supplied by Verizon (a 7500) and I've been able to use it to meet all my LAN routing needs in the home.  I have an ethernet connected desktop, a wireless lap top, a kodak wireless printer, and a wireless sony blu-ray player, all talking to the 7500.  I can do everything I think I need to do with no help from an additional router. 
Both computers can talk to the printer, and to the internet.    The blu-ray can talk to Netflix on the internet, and to get content from a DLNA server on the computers.  The blu-ray and the printer don't talk to each other, but I don't care. 
So why does everybody run out and buy a router, and then face the necessity of configuring their DSL router/modem in bridge mode?  What does this buy them? 

Answer 1

Thanks for your response.  I didn't mean to imply that there were no valid reasons.  Just that I didn't know what they were.
The people who have as much networking experience as you do probably all buy their routers for good reasons.  They also probably know all about when to use bridging mode.  It's the poor slobs that buy their first router at some office supply store, because the salesman told them that's what they need, that interest me.  Many of those people would be better off learning how the box from Verizon works before spending more cash for another box.
Your response will be especially valuable to me once I max out my 7500.  So I plan on marking it as the solution unless I get a preferable response in the next few days.
Meanwhile, I'm interested in the 6100.  About all I know is that it only has one ethernet plug instead of 4.  But I presume it can still operate as a wireless access point for multiple devices.  Correct?