The thing with that is that Swamp Thing doesn't have the initial walk speed that Scarecrow has. Essentially, coming out of crouch and taking a step forward, Scarecrow trumps Swamp Thing. You can try it for yourself. Set Deadshot to "infinite" wrist shot and start fullscreen. Crouch walk your way forward and you'll see Scarecrow gets closer to Deadshot much faster than Swamp Thing easily. This new trait mechanic seemed the answer to alleviate his slow walk speed but nope. He's still shit.
No doubt Scarecrow has a better walk speed, better mobility and better reach in the air. But he also doesn't have a full screen reaching special move (clone) nor a semi full screen grapple. He literally has to get in to do anything but by no means am I trying to up-play him i'm just stating facts. I'll give it shot when I finally get home though.
Scarecrow doesn't get armor added to a full screen anti zoning move with his trait. If swamp things trait is intended to be implemented only during successful pressure... then why do it? Why not just combo for more damage and keep the spacing in a range that's ideal for swamp thing?
Swamp players can probably tell you about their worst matchups and why this change gave them hope... but if they knew trait was to be used as you said they would have not had any hope.
You're right, Scarecrow doesn't get armor, but despite few Scarecrow players using it often, his DB2 eats projectiles. I've been using both characters exclusively the last 2-3 weeks so I have been giving them honest shots. The reason you would still use his trait is the same reason I would use Cheetahs trait...when the opportunity presents itself. She poses no complete full screen threat because even her furthest pounce comes up short and is easily fully combo punished with nearly every characters S1 as an anti-air.
Point being it's a tool that has to be used for the job it's suite for and thats once i've gotten in range that it can be implemented and utilized to my advantage.
As far as why not just combo for more damage is the same reason why a lot players sacrifice max combo damage...Okie and setups. Especially against highly mobile characters (Batman, Supergirl, Superman, Firestorm, or non-projectile characters) who rely a lot on their mobility for footsies this will cut down on their jumping or dashing putting you in a position to better impose your gameplay. This may be theory crafting but it's logical. I just want others to think outside the box and come up with some usefulness for what has been given. It may not cover the glaring flaws, but I believe there is still potential and
@MILE_HIGH_CLUB is presenting some options.