1. Allows you to take a shot, then overwatch/reload/throw grenade/etc. Very, very useful ability that can be cheesed with ghost grenades. You cannot shot and then rocket however.
2.Suppression is worthless and the shredder rockets synergy with 2-3 mines laid from stealth on a sectopod is too much to pass on folks
3. Took a major nerf from 100 to 50 but yet still is way more useful than two reaction shots in a single turn... That says something

4. One of the most OP items in the game is the new "ghost grenade" (ie. the "get out of jail free" card in this game) and with two slots it means you could carry as many as four if you really wanted to cheese... (shoot enemy, throw ghost grenade, rinse repeat) Suppression is worthless/outclassed and larger radius kills more civilians than enemies...
5. The only people you will be using rockets on are sectopods or in "get out of jail" situations, meaning the extra 1-3 damage doesn't mean spit. Having an extra rocket on the other hand is nice. All explosives have synergy with mines from MEC's