For people willing to commit insurance fraud putting a few scratches on the lock and door to make it look legit isn't really that much of an effort. Are insurance companies actually conditioning their conclusion based on this kind of evidence?

The real value of a lock that's hard to pick is that it forces the burglar to carry more tools and use noisier, time consuming methods. All of this makes the break-in far more obvious and detectable much faster by neighbors, or anyone really, even the owner.

And you want to make the job harder and riskier for the burglar so the bar is higher for how willing they must be to go through with the job.

Most burglaries are "blind" ones, meaning the burglars have a reasonably good idea of the job's value and difficulty level. So if you have a lot of valuables you have to do your darnedest to raise the job's difficulty: make the break in take time, be noisy, and generally draw attention, or forcing the robbers to leave a lot of evidence behind.