IMHO OBSERVATIONS & CONCLUSIONS:
First, I agree that roleplay-focused guilds on the Horde side of BB are very rare, unlike WrA for example. I agree that causes are:
There are some active RP guilds, but you need to spend time in-game looking around to track them down. I have seen an orc-focused guild periodically advertising in Orgrimmar, and a tribal style guild advertising generally and active in Thunder Bluff (although both guilds admit any race interested in that theme). In addition, this thead has mentioned three guilds (Darkmoon Faire, All Who Wander, LustMord), and mentioned a fourth (Royal Apothecary Society).
Unlike WrA (Wyrmrest Accord), the most active horde RP server for retail play, just wandering around looking for RPer “hangouts” and activity isn’t enough. You actually have to devote serious effort to tracking down guilds, talking with their leaders, and trying them out to determine which one you might like.
TL;DR SUGGESTIONS DEPARTMENT:
As some have mentioned, I do wish that existing RP guilds would advertise both recruitment and their events in-game a bit more.
Personally, I have a preference for guilds who want the main guild chat channel to be IC. The few times I’ve seen this, it greatly enhanced the roleplay aspect of the guild, as well as forestalling people who join guilds out of a need for attention/drama. Alas, IC guild chat is still rare, despite WoW’s ability to form special channels for OOC as needed.
I have also seen guilds (on WrA) use simple d20 rolls for managing RP events, while avoiding all the baggage of a formalized d20 system. After all, not everyone is familiar with d20 style D&D, much less trying to map D&D character classes onto WoW classes!
Finally, I would encourage all RPers to be IC in everyday interactions with other horde members on the server. Although events sometimes need chat in private channels, remember that “you reap what you sow” in RP, as in much else. Therefore, the more you try to interact IC, the greater your chance of encountering like-minded individuals.