Remote controlled ships
are just ships equipped with standard weaponry aka they're useless.
Kamikaze attack runs
- at impulse or warp - have limited usefulness.
We know this because Starfleet officers/ships had no problem comitting suicide during the borg invasion. There are at least 3 established cases of a Starfleet ship engaging in a suicide run: in "Destiny", above Kithomer and above Deneva; in 'Full circle', Voyager.
Such attacks only worked when there were special circumstances involved - for example, the starfleet ship was out of phase or the borg cube was heavily damaged.
Suicide runs at warp are equally ineffective as impulse ones - if they had worked, half of Starfleet would have used them against the borg.
If the Verithrax managed to destroy a cube with such a kamikaze run, then either that cube was already damaged by other means or the romulans carried an exotic weapon on board.
- "Nemesis' established that the romulan military didn't have them. Also, if the romulans had used thalaron against the borg, some federation official or Picard/Geordi would have comented on it during their hypocritical/treasonous posturing.
- not part of relaunch continuity. Until a book establishes it as part of this continuity, it's just fanon.
- a plausible candidate.
'Insurrection' shows the potency of such weapons - and their danger: unpredictability.
'Serpents among the ruins' establishes that the romulans have such weapons and used them at least once before.
About repercussions resulting from the romulans using metaweapons:
All other powers already knew the romulans had metaweapons (subspace weapons, for example).
All other powers had metaweapons of their own (for the Federation - Genesis, Thalaon, TOS, TNG establish half a dozen more).
This means, of course, that no one should be alarmed about the romulans using metaweapons - and planing to invade Romulus or something alarmist like this.
There could be accusations of breaking the various treaties forbidding the use of such weapons - of course, considering the situation in 'Destiny', I doubt they'll be too loud.
About a cultural division existing in the romulan empire:
Prior to the division of the romulan empire into 2 states, there was never any intention on the part of the scenarists/writers of depicting the romulans as being culturally divided on a large scale.
After this division - I guess such a cultural division can be retconed in.