This is the universal rule for armour. ALL armour is going to impair mobility, be it Cuir Couilli or Plate or modern Kevlar. And, by and large, similar coverage of armour, regardless of type, is going to weigh a comparable amount (at least until you get into the later Plate, which was both lighter and more protective, while not needing the layered protection of gambeson and maille underneath).
But, different armours DID require different amounts of work to make and don, and did offer different degrees of protection for different situations. Even during the late medieval period, particularly paranoid individuals wore byrnies under their clothing to protect against would-be assassins, since it was very difficult to stab through or cut maille. It was useless against force impacts, but it protected very well against small blades and was quick to put on.
Ultimately, anyone who can really afford good armour is going to have multiple suits, and is going to wear what they feel is appropriate for the situation. If they are expecting a full blow, drag-em-out fight, they have little reason to wear anything but their heaviest (or rather, most protective) armour (unless there are extenuating environmental considerations, though many of those aren't easily predictable). If they're expecting to ambush a caravan or travelling party, then something lighter and less complete is more likely.
If you don't have the choice, because of a lack of ability to buy good armour, then you're far more likely to just wear the best you can afford.
That's really one of the necessary absurdities of RPGs... you almost never did any traveling in armour. Even during the crusades, when you could reasonably expect to be ambushed at any point, knights only really tended to wear their armour when they were sure they were going to fight. The same goes for weapons, really. You rarely carried more than a dagger when you weren't actively trying to kill people. Travelling in armour just wasn't something people did very often...
But in an RPG, with an emphasis on exploration and adventure, having you rummage through your cart and put on your armour every time you see something interesting is a serious hassle...