These Techies changes.... I don't get them.
They've definitely nerfed the snowball into landmine into suicide combo. They've weakened Techies' lane presence in general; using landmines to clear creeps and harass the enemy is now less effective.
But was that ever the problem?
The lack of stacking marginally reduces the utility of landmine traps. But creating those traps doesn't cost any more mana, and it doesn't take any more time. You can now create more traps--no 20 mine limit--and you can create traps of different sizes; I suspect that in many cases, the 3-mine first blood can now be a 5-mine first blood, at a lower mana cost.
This surely makes Techies more annoying, not less. It's going to mean even more mine traps spread across even more of the map. The reduced lane presence increases the incentive of laying traps, and the traps are now (overall) increased in number. Isn't this encouraging precisely the wrong behaviour?
The ability to destroy mine traps without exploding them is lame, mind you. It makes sense, as it means that short-range or melee supports aren't penalized anything like as much, but it's lame.