You can adapt to losing Thermite and Thatcher; they force you to take different routes. When you lose either of them, you don't lose your offensive capabilities; they don't grind your approach to a complete halt and force you to crouch at every barricade (every single one) to check for a laser.
Let me just point out what this "laser check" solution everyone's talking about risks for the attackers:
As if breaking a barricade wasn't already an enormous risk, now they have to do it for every barricade. Kapkan could simply barricade every door upstairs, slowing the assault down by an absurd margin.
A player could sit in a barricaded area, prone or crouching by all the barricades. When a player goes to punch the lower half to check for the laser, they've left themselves wide-open to a sudden attack. And because Kapkan's traps are so dangerous, they could be on any of those barricades, and any of those barricades could have a player behind them. Normally, the attackers could spare some time to run drones through and such, but because every single barricade--no matter where it's located--could have a tripmine behind it (because they can't see it), they've suddenly had to slow their approach down and can't afford to waste a single second.
Breaking barricades generates noise. This, above all, is the biggest issue. Attackers are slowing down, taking extra time to break barricades (that third hit is time wasted when two hits and a jump could spare you the trouble).
The point of Kapkan's traps is to make the enemy pay attention, not force them to assault at a snail's pace. The spike is there so the enemy can't say they weren't looking, and I do feel it's too obvious at times. That said, it's still there for a reason, and removing it removes his sole balancing factor, turning his trap from a punishing factor for the attackers (you didn't look before your leaped) into a pure advantage for the defenders.
Not to mention this: breaking those barricades every single time, especially when the defenders get spammy, would be tedious as hell.