Love the attitudes, love 'em.
What is being talked about sounds more like a concept that has been in place in some departments for several years; I think that it's just gaining wider traction because there have been quite a few (relatively speaking) active shooter/bombings in the last 2-3 years. There was a write up done (may have been in JEMS but I don't remember) on what a few places in Virginia started to do after the VT shooting; essentially sounds like this.
Aside from the normal issues you get with large scale incidents (large numbers of patients, patients running and turning up far from the scene, crowd control, etc) the issue with active shooters and such is that the most seriously injured people who might otherwise have been salvageable end up dying because it takes 30+ minutes for them to reach treatment. This sort of response is geared to fix that problem.
The goal of this isn't to send paramedics up to the very front, or if there is still firing to where that is, but to provide them with body armor, group them with several officers, and send them into areas that have been rapidly swept through but not technically "cleared" by another team to bring out any victims; ie they are going into the warm zone. Is there some added risk? Sure, but in reality not as much as people will think. It is also very worth remembering that in larger buildings, it will literally take hours for the entire building to be "clear," if it ever truly is; think of how large a mall is; do you really think it is appropriate to wait until the entire building has been formally cleared before EMS should enter?
With a bombing it is still a little different; secondary explosions are a real and definite risk. The only way to truly mitigate that is to be very, very far from the initial blast. Which still leaves the issue of how do you get patients to ambulances, and who will be doing that.
The risk to EMS in these situations can and should be minimized as much as possible, but the simple reality of the world we live in is that these types of situations will likely continue. EMS will either evolve and change to fit into the role that it is now needed in, or it won't. At face value this isn't a terribly complex concept, it just takes some practice and the involved groups buying into it.
Unfortunately, due to misinformation, misunderstanding, apathy, and a long history of the same, it probably won't happen.