I run a TLR1 on my primary SHTF rifle and don't see the need to ante up for anything greater than that. I don't usually shoot at night, however I would like some illumination if the situation called for it. If I position my stubby VFG right where I like it, the TLR1HL is plenty usable. I believe it is 600? Lumens. I could be wrong. But it's plenty bright.

I see many people run Surefire 300s and 600s. What advantage does a dedicated rifle light offer that a "miscellaneous" general weapon light does not.

Some people prefer the push button switch over the toggle style, for others it's the ergonomics of being able to place it in a specific location where a pistol light might not work or which would force them to change their natural grip. Rifle lights like the Scout and Millennium series can also be upgraded much easier than nearly any pistol light.

Weapon lights are modular upgrade able and in my opinion more rugged

Your current light I would have on a handgun or mounted to a helmet personally

I run a surefire m952v of course I wanted IR/White light capability for my pvs 14

That and again there upgrade able

Also as the matchbook pointed out , the clicky switch with a guard is preferable so I don't accidentally turn the light on while handling it

Nothing like going to grab your gun out your safe in the middle of the night and bumping the switch blinding yourself lol

the scout lights from SF are a bit slimmer and, to me anyway, seem a little more robust than the TLR-1's.  Personally I don't really like the rocker switches of pistol lights when run on rifles.  I just can't get my hand in a good position to operate them comfortably.  The push buttons on the scouts and regular tube lights work better for my grip and what not, so that is how I roll.  Also, I think that the tube lights are sealed a bit better for water intrusion.  I have a TLR-1 on one of my pistols, but I forget how well it is sealed.  That pistol usually sits in the safe and I have another pistol with light for HD stuff.  

Really though, if it works for you, then more power to ya.  Why mess with something that is already working?  If you are curious if something else out there is better, try to find someone that has a different set up and see if you can handle it to see if it will work for you.  other than that, I doubt you will miss much going to a dedicated weapons light like the Scouts.

The only real issue is how easy it is to accidentally activate it if the weapon is in a vehicle or whatever. Bedside use is fine.

This. However, there's not a damn thing wrong with using the tlr as a weapon light. It's rugged enough despite what some say. Take my word.

Basically some peolpke like to pay hundreds more for a light when another less expensive light can do the same thing and is just as rugged.

Just do your research and don't get pressured into buying a light just because it's two or three hundred dollars.

The weaponlights have a different beam focus that is slightly tighter than the pistol lights.  Pistol lights have a wider beam throw for close-range use, whereas the rifle lights from SureFire (M300, M600, M95x, etc) are designed for longer range ability along with CQB.  

The weaponlights are more modular, typically have different mounting options instead of the static one of the pistol light, and have replaceable components.

The dedicated weaponlights from SureFire are substantially more rugged and durable than the pistol lights.  This includes the SureFire X300 series, which is a pistol light.  The caveat is that most users won't use and abuse their lights in such way to see that extra advantage.  The extra durabilty of the SureFire weaponlights lives at the extremes, where most people generally won't take their weapon lights.  
I've seen lights get thrown, dropped, launched off moving vehicles, get run over, smashed through windows, smashed into doors, smashed into skulls, blown up, covered in blood and water and ice, and everything else.  I have seen a lot of various lights broken, and I have personally destroyed three pistol lights.  The SureFire lights are by far the most durable of all lights I've used or seen used.  I think it's fair to say that the concept of durability is subjective to intended use and the user using it.

That being said, do you need that durability?  For most people the answer is NO.  
If you are okay with paying the cost, then I would wholeheartedly recommend buying a SureFire weaponlight.  If spending that money is hard to justify, don't.  A Streamlight TLR-1 HL is good light and it will do everything you need it to do.