I could be completely wrong here, but I would guess that the majority of MW's customers purchase or rent suits infrequently; old measurements are likely to be inaccurate by the time a customer returns for a new suit.
More generally, I really don't see the point of paying for custom-fitted clothing without first confirming that the clothes are going to fit.
this is true, although most people won't get taller, they'll get wider, and most rentals have adjustable waists, and coats won't change size that much.
a neat alternative would be, imo, to have them keep your old measurements, but store them online where you can see/edit/update. old ones prompt for re-measurements
You should be measured every time you rent or buy a suit or tux. Men's Wearhouse would be doing their customers a disservice if they just handed out suits based on 6+ month old data.
They'd need to have people opt-in, otherwise privacy nuts would be complaining that "MW is holding on to my personal clothing sizes for years without my consent!".
Opt-in would be fine, but I have to say as someone who is in the process of aging, I'm not the same shape I was 5 years ago. 6 months probably, but I doubt for many people the data is actually usable without a refit after, say, 3-4 years.
I'd expect they use the data in aggregate to figure out what sizes of clothing to stock where to keep latency and transportation lower.
It doesn't seem that much of their variable cost would get shaved off by already having one's measurements, which makes me think this wouldn't help them with a lowest-price strategy. Maybe a higher-end market focus.
But as other have already said: body size data can be expected to expire often. I'm an edge case, but my weight has oscillated between 195 and 165 a few times in the last year.
More generally, I really don't see the point of paying for custom-fitted clothing without first confirming that the clothes are going to fit.