Well the thing is that right now you do have to fight at some point or you won't get enough points so you either try to get as many kills as you can between the large crystal spawns or end up having to fight at the end, often ending in a 1v2 if you are in the lead. With the change, just the kills you get left and right will be enough and it will allow for an even more defensive strategy.

One problem is that you have to choose between attacking the crystal or attacking the enemy, with the first option netting a lot more points. It is very unlikely you will wipe a team in the amount of time it takes to destroy a crystal. At most, you will kill half the group and even that is generous. In that case, you would get 120 points and they would get 240 (300 - 60). You would need to kill 20/24 to break even. If kills were changed to +20/-10, it would take 10 to break even. That might encourage people to contest.

In contrast to Shatter, Seal Rock required you to fight over the objective to have a chance at capture. We went from having to both fight and achieve objectives to fight or achieve objectives and that's not a very healthy situation in my opinion.

* Just a disclaimer that I started playing late and have very limited experience with the Cartenau Frontlines (a few odd 24 man matches from roulette) so I can't really comment on how they compare to the current situation.
However, from what I've seen, the large nodes actually did considerable damage to the players which would open up opportunities for kills. That kind of risk is absent from Shatter. The addition of a damage reflect from the crystal which has been mentioned in one thread could be a nice way to spice things up if it applied to everyone.