This is an interesting discussion, given that it reveals so much dissociation.
On the one hand there's consternation over tins not holding up because they SHOULD hold up because the tobacco needs aging to "improve" over years and years, long after it's purchased, VS the tins aren't supposed to hold up long term because the product is ready to smoke upon release. The tin may be sealed, but not with the intent that it will hold up long term. Short term, the contents will have extra water added to them to keep them from drying out white making their way through distribution and retail sales. A robust seal isn't needed. So Hoggarth's response is the same as Germaine's: stop faffing about.
Unlike some manufacturers in the US, Denmark, and Germany, who stick you with the maturing process, the better British blenders release a product that is already been aged to the point that they think it represents what they want their product to taste like. It's ready to go. Just pack a bowl and enjoy. Just stop by your tobacconists and pick up a tin.
All this talk about their products "needing" further aging to become "improved" are essentially an insult to the blenders, who have already done this. Stop "faffing about" and just smoke it.
On the other hand, you can't just stop by your neighborhood tobacconist because he closed up shop. The nearest tobacconist is 50 or 200, or 1,000 miles away. Maybe you can find some of these great blends on line, if they show up, which is not often, and where the piranha wipe the carcass clean in minutes. So actual distribution is not resembling in the least how it was 40 years ago.
People will buy in greater amounts to have some on hand, whether they are buying to age or not, because distribution is a fucking mess.
So what to do? End users, jar the tobacco or seal it up in Mylar if you like how it changes over time. It won't be what the blenders intended, but who cares. And if you don't care one way or the other about aging, just want to have some on hand to smoke when you feel like it do the same, jar or seal in Mylar.
Blenders? We love your creations. Conditions aren't what they used to be, it's unpredictable in the extreme, so going forward, how about recognizing this unpredictability, factoring it into your future packaging decisions, but no strong pressure seal can easily pried with fingers, let's be clear about that.