As a basic defense firearm at more than pistol range, but less than 150 yrds I would think that you would want to injure not kill the attacker(s). With that in mind, why would you not want to use a 17 HMR? Accuracy is there out to 100yrds, penetration is there, wounds that would put the aggressor out of action but not kill (takes other bodies out of action to attend to the wounded. Whats your opinion?

It is rim fire for one so not as reliable as center fire.

Lot less proven firearm designs available.

Doesn't carry the bullet weight nor the velocity.

Reliability; have not had a miss fire out of the 1000 rds I have shot
Agree on the design availability but there are semi auto available
bullet weight and velocity, not trying to knock them over, just want to put them out of commission. Note, shoot standard 223 or 5.56 at 1/8 inch thick steel at 60 yrds and see if it penetrates, 17HMR will.
just looking at the alternatives to buying a AR style rifle, nothing against them, just not my cup of tea.

I own a 17HMR and have not been impressed with it performance of game.

Use what every you want but the 5.56/223 out classes the 17HMR by far.