Do objects (like doors) start with a base Defense of 10?

When Damaging Objects, considered to be Defenseless:

Inanimate objects are defenseless by definition and therefore subject to finishing attacks (see the Finishing Attack maneuver): essentially, you can choose between making your attack on the object as a routine check or, if you make the attack check normally, gaining an automatic critical hit if your attack hits, for a +5 bonus to effect.

This is all fine and good, except that the last time I had to adjudicate this, with someone trying to kick a door down, they objected to me starting with the Base 10 defense for the door, namely they chose to Power Attack, and where already damage shifted, and completely missed the door. I can kind of see their point that a door shouldn’t be that easy to miss hitting. I think I described it as more of a "glancing blow", that they were trying so hard to hit it hard that the blow just skidded off of it. But the question does remain, should a Defenseless object the size of a door start with a defense of 10 such that the average bystander has a little more than a 50/50 chance of actually hitting it if they’re trying to hit it hard? Am I reading the rules wrong? Did the player maybe just get a little too greedy in trying to do more damage?