My thoughts are that I'm going to be in this industry for another 30 years if not longer so I want the title to hold and have when I need it. I work directly alongside P.Eng. engineers so its much easier as my work is a lot closer to electronic engineers than most software.
For someone not requiring it there are often provisions on each regulatory body's to get it down the line by providing cases of past work experience validated by a P.Eng. no matter when it happened.
I suppose I am lucky, my immediate supervisors are both P.Eng because of the nature of what we do. I agree though, I don't think it matters much in the software field. I don't have the required amount of work experience yet, but as a Computer Engineer working in and interested in the software field I am on the fence.
You are supposed to submit work experience under supervision of another P. Eng. which are not very common place in our industry. I believe you can apply for exceptions to this rule though.
I personally haven't bothered following through with my P. Eng. status as I am not yet convinced it buys much in our profession (vs. the other fields of Engineering).