Currently in the game, it encourages splitting the team up to cover more ground, so with your proposed change in mind, if the team is split up 2/2, the monster has a 50% chance of being domed 30 seconds earlier. With the cross-class variants, telling characters by the smell silhouette is slightly harder.
Sure you can kill the trapper to get rid of the possibility of 30 seconds reduction to the next dome, but then no hunter would dome you without a full team anyway. You could have killed any other hunter and achieved the same if not better results. This means that the trapper is insignificant to the monster, just a nuisance, which is the same as it is right now.
Also, even with the trapper planetary scanner, it’s 50/50 depending on the monster in case of it double backing, so it’s not even up to skill that you happen to bump into the monster 30 seconds earlier for a dome. It’s a buff, but it does nothing in terms of skill, it just differentiates the classes more. The only change for the hunters would be that the trapper needs to chase the monster, which it should be doing in the first place. There would be no playstyle difference on either side.
Back in legacy, trappers were the only one who could dome, which gave them an important role to perform in the Hunter’s side. And if you wanted the dome to get down, you had to incap the trapper, which made the trapper an important character to the Monster. Which is balanced cause the class is important to both sides. You need to give or rework something to the trapper to make him important on both sides.