A too-common theme I have seen across these are that people like OpenRA in general but feel let down by what they see as arbitrary and unnecessary changes in the RA mod.
Then a greater effort needs to be made to explain why these changes are not arbitrary. And if they are arbitrary we need to ask ourselves why the change was made in the first place. IN either case, the point of this thread is to figure out if adding a new unit is necessary. Additionally if it is necessary, the sea scorpion does fit naturally into the cnc world as it follows the same line the flak truck did. Those against the change because it breaks away from the classic game more than likely just want the old game running on new computers. I agree with sircake and law that those people should be directed to cncnet OR a classic RA mod should be released. Without splitting into a "classic" and a "modern" mod the
best option would be to have a checkbox called classic that uses only the classic rules and let the modern rule set be the balanced rule set. This way if someone wants to have their tank spam, no fog, hind on soviets, apc on allies, imbalanced but original game they can. The only advantage to splitting the mods would be to allow the modern version its own campaign (Which would be quite fun FWIW)
The way I see it the stakeholders lie on a spectrum where offline is one end and online is the other. Those offline are the ones more generally interested in the campaign and the nostalgic feel of this old, but great game. Further towards the center are those still offline but might play skirmishes against the bots/ fiddle around the the map maker for their own desires. In the middle of the spectrum are the people you mentioned who play openra with coworkers after work. These people go online solely for the purpose to play with friends. After them are the casual players, the players who play big team games, gods divide, etc. And finally at the end you get the competitive players.
If the majority of openra players are from the first 2 examples on the curve than openra is a sin. Coincidentally, those are the people most likely not involved in the community and either drop the project when changes are made that they don't like or move over on the spectrum when they do voice their opinion (and its explained why the changes are made.) The other side only benefits from balancing done by the competitive community.
That people are "disappointed" because you did not comply 100% with the original while expecting improvements is insanity.