while my own country only used it in the Strv-103
Hm, rather nice design there. My own favourites are the Leopard 2 and the T-84.
Overall, mecha... not a competent weapon. Now. With the current tools available to us. However, the platform does have potential. In terms of agility, and handling irregular terrain, the human platform is quite exceptional. If the battle environment changes, something mechalike could become most useful.
Now, mind, you're never going to see extreme-size mecha on the ground except as a failed wunderwaffen. The advantages of that size are solely in larger weapons and armour. Which is good. The problem is that a tank simply does both of those far better than a mecha, outshines the mecha on speed over ground, and in a smaller package - and will continue to do so as long as weapon/armour size, stability, and exposed target area are factors. The advantages of the mecha platform on ground disappear at that size (ground pressure means the mecha sinks into cement, let alone actual battle terrains, and agility doesn't help it much if it's so much larger). Now, in space, extreme-size is possible, and can in fact be desireable (mobility comes straight down to thrust/mass ratio, so slap another kilogram of thrust on for every kilogram of mass you add and the Hulk starts dancing, and you still have ever-largening weapons and armour), but of course costs out the ass - so in space, the size limit is roughly based on economy, ie, how many of those can you afford. Plus whether you want to actually put them near gravity or not.