Being very honest with yourself about how you use your plane and why you are getting additional ratings is really important. I've now had my PPl for over 6 years and my IR for 4. I thought I would use the plane for going places and the IR would be really important.
As it turns out, I don't go anywhere. I never use the plane as transportation. It is purely for enjoyment. Just like having a boat on a lake, I go for airplane rides. Therefore, if the weather is bad, I don't go. I keep my IR certificate current, but I don't fly anywhere near enough to stay proficient. I wouldn't think of flying intentionally in IMC with my current level of experience.
That said, if you can afford it I would still recommend getting the IR. First, it was fun. I enjoyed the challenge of the training and learning more about flying. Secondly, it significantly improved my skill level. I am able to multitask much better as a result. My control of the plane is more precise and gentle. My anxiety level has decreased. Third, I am much more comfortable operating in larger airports and congested airspace. I can fly IFR procedures, I just only want to do it in VMC. Fourth, there is some added safety. I am confident that if I were to get into an IMC situation inadvertantly, I could get myself out. Such situation occur and they don't require clouds. Night flying or hazy humid days heading into the sun can put you into positions where you are really instrument flying even though it is technically VMC.
Can you achieve all of those advantages without actually getting the IR? Absolutely. The IR does provide the structure and incentive to really work at it and keep you on task. If you have the money and want the challenge, I'd go for it. If you intend to use the plane as a practical tool and fly anywhere except maybe the desert southwest, then I'd definitely get the IR. If you are like me and just doing this for fun, then I'd think seriously. I'd get it for the reason I stated above. But if you think you are going to use the IR, then you have to be committed to fly IFR, in IMC, on a very regular basis. It is not something that you can do once every couple of months as a lark.