It's not as though this is some newly discovered thing. Perspective doesn't get fixed when shown on an older TV.if you think that the audience could in fact have spotted the FP painting so easily
Like I said, done for convenience. But I disagree with the level of work vs gain. The angles on Picard and Darren are filmed separately anyway. They could have turned around on the set (filming each side facing the same direction in reality) and no one could tell the difference.assuming they only had the 1 in TNG, then completely redressing the set like you propose would have been a lot of extra work for very little gain!