As far as I'm concerned, the value in the MSD card (or the rating) is the value you give it and your reasons for wanting it. If your goal is to challenge yourself in attaining the rating, then why not? If you take the easiest possible classes just to get the card, I can't see much value in that, other than card collecting. If you take classes and then ended up being able to apply for the card if you want, great - if you see the card as a recognition of your accomplishments, great, get the card. If the card doesn't matter to you, fine, celebrate your accomplishments without the card. At this point, I don't have the MSD rating, and I probably won't get the card when I qualify for it, but that's just me. Right now, I'm just curious what I'm going to qualify for first, MSD or MSDT, time will tell.
As far as showing a pro card to a dive op for a fun dive, if liability on a fun dive is your deciding factor about whether or not to do DM, then you probably shouldn't do DM.
As far as showing a pro card to a dive op for a fun dive, if liability on a fun dive is your deciding factor about whether or not to do DM, then you probably shouldn't do DM.