I just watched that trailer and I think never played any Front Mission games, but it looks an awful lot like MechCommander 3 to me--which would be fantastic. I loved those games when they came out back in the day. Speaking of back in the day, I used to play a game called MechForce that was pretty fun and someone is apparently working on an open-source remake called MechFight.
This sounds like every open-world game to me. The only ones I remember playing that had much in the way of creativity when it comes to side missions are The Witcher 3 and, to a much lesser extent, DA: Inquisition. I'm in the middle of Mafia III at the moment and it fits that description to a "T."
Oh, yes - Mafia 3 definitely has "UbiSoft" style open-world game written all over it, once you get past the Mafia 3 Demo / Intro section.
I think back in the day, most side-quests weren't say collect-a-thons + take over these area missions (i.e. see Homefront TR, Mafia 3, AC series, FC series, etc). More side-quests in open-world games were those Loyalty style missions in those days, like you'd see in Mass Effect 2+3 & Dragon Age: Inquisition. These Loyalty-style quest-lines in those side-quests likely will be shorter than the main-quests, but usually...those side-quests still had set-pieces + more meat to them than the usual MMO-style of quests (Kill X enemies, find X characters, go to X areas, find X items, etc).
It seems like more games - especially in RPG's - are doing more collect-a-thons and MMO-style quests and less of the Loyalty-style quests. Probably easier to do so, to keep the costs of voice-acting, writing, choices, and other things down.