Obviously, for the genius technical minds that browse this site, leasing a router that is just pulling basic NAT/DNS/firewall duty is a cardinal sin.
But also consider this: If someone calls me with an internet problem and they have some combo router+modem on lease from Comcast, I can just give them a quick 5 minute troubleshoot session followed by the 800 number and wish them best of luck. It's all about your perspective. $150 a year for peace of mind that the cable co (as evil and shitty as they may be) are required to ultimately repair/replace this hardware if problematic.
At the end of the day, I'd rather not have to be on the hook for an off-handed suggestion that someone should purchase their own router/modem hardware and subsequently be expected to configure/maintain it. I expect most on this site have experienced the role of providing free tech support for friends & family. Just because I would never use a leased router or modem does NOT mean this is the correct option for everyone I know.
I do not like big cable or their business practices. I simply value my time more than the $150 annual savings an arbitrary consumer may realize, considering my role in society as a technical person who is unfortunately just 1 quick phone call away. I'd much rather Comcast spend their time and money fixing everyone's internet for me. If they have to bill non-technical customers a little extra to make this possible, that's totally fine by me.