Ok, here's my take on it.
I don't really have an issue with it.
GameFreak had a tightrope to walk. Because when they've done deviating remixes in the past (see HGSS' Goldenrod City) its been badly received. Playing it safe and being fairly close to its original sound was probably the safest move.
I think my biggest complaint is them not toning down the brass instruments (the infamous Trumpets, and the more present but undermentioned French Horns) in exchange for more strings.
The bigger problem with the OST in my opinion is the lack of coherency between the RSE remade tracks and the new tracks added. The piano pieces, the Soaring themes, and Wally's first encounter theme are perfectly fine. But Zinnia's and many of the cutscene tracks don't fit. I'm not saying they're bad pieces or anything. But they don't fit thematically.
Take Wally's Battle theme. Guitar soloing to emphasize his character development? Ok thats good! But the rest of the soundtrack is orchestral... You can make epic orchestral pieces! Look at Red's theme, Blue's Theme, Vs. Dialga/Palkia, Vs. N. If you want Wally to have this electric guitar solo... add more electric guitars into the primary soundtrack so its not so jarring...
So my final response - I think they did good, but the failure to synergize the old themes with the new really made it fall flat.
On plus side, it at least makes it easier to have remixes like
this since their so identical.