Of course it's better for them if the CAN make you install it. Just like it's better for a company if they can convince you to sign up for something, or at least give them your email. But the point is that if you can expose your clients to your service without all that, then you should avoid introducing the hurdle, you don't want to scare anyone off.

So: make it possible to use the service without any hurdles, but _try_ to get them to agree to as much as possible.