Do you NEED one? Probably not, if you only plan to fly in gin-clear VMC and can guarantee there will be no sneaky clouds to creep up on you.
Should you do one? Almost certainly YES. It will hone your flying skills to a much sharper level (don't start the IMC till you have enough post-PPL hours to have got comfortable with handling the aeroplane). It may well save your bacon one day when that sneaky cloud catches you.
Many times I've been told "I don't want to fly in cloud: there's nothing to see and the passengers don't enjoy it." Only partly true. I've taken off into a 1000 foot cloudbase many times, flown for 20 minutes or so into bright sunshine, and had a delightful few days away from home with family and aeroplane. We've then returned into 20 minutes of IMC to land back at wet, soggy home.
Yes, there is a risk of banging into another aeroplane in the cloud. However, there hasn't been a collision between two aircraft in IMC outside controlled airspace in the UK since 1943. There are many more serious risks that any aviator undertakes, even in CAVOK. Also, flying in IMC there tends to be less traffic around, you fly above MSA/SSA, and there is almost always an ATC unit who will give you a service.
I find that most objections to the IMCR are from people who failed it, from retired Air Vice Marshals who think it's a "get out of trouble only" rating, or from commercial airlines who resent PPLs intruding into their sky.
In reality, if you use it much you may choose to go on and do the new course to convert to a full IR. I went down the FAA IR route before that option became available, and found that the IMCR plus about 100 hours of "sole reference to instruments" flight using it was a good preparation for the IR.