Probably the most anticipated thread ever. I'll make it a list of RP-friendly features in SWG, arranged in a convenient flow-of-though order.
1. Really obvious roleplayer tags - see them allover the galaxy, and they're hard to miss
2. Roleplayer search function - shows all the RPers in your vicinity
3. Sitting on chairs and ground - not just stand-around gatherings
4. Prose parser chat output - makes full sentences out of emotes and speech, with the moods, languages and speech types included (E.g. Drrlirarl complains agrily, "Rrowrr!" in Shyriiwook.)
5. Moods - these come with different standing animations, dozens if not a hundred available
6. Speech types - these come with different kinds of chat bubbles, dozens if not a hundred available
7. Chat bubbles - these help you keep track of who's talking and emoting
8. Languages - You can learn them all if you want, or leave out the ones you don't want your character to know (they will appear scrambled then)
9. Housing - laying down roots is important, and you can place houses in the real world, anywhere that's free on the large maps
10. Large maps - for you explorer types and others, it's nice to have a coherent large area to roam and play
11. Decorating - you can put down practically any item in your house, whether it's meant as furniture or not, and place it quite freely even off the ground, which makes for awesome-looking interiors
12. Multiplayer spaceships - decoratable just like a house, with turrets for mining or fighting, pilot seat, co-pilot seat, damage that can be dangerous and repairable in the interior
13. Space - just awesome, you can take off and fly to another planet, mine asteroids, RP jobs available as escort pilots and such
14. Technological world - allows instant communication across great distances without breaking immersion
15. Interesting world - diversity ranging from criminal scum to stormtroopers, peasants to force users, living on the edge to toiling in mundanity
16. Established RP community - several of them, actually, ranging from adventure or light RPers to seriously hardcore people just RPing daily lives of their characters, scheming and plotting
17. Weather effects - seems pretty basic, but a sandstorm on Tatooine or pouring rain on Rori is no joke when you're IC
18. Day/night cycles - just imagine nightfall when you're out hunting on Dathomir
19. Beautiful graphics - some things that will make you really go "wow" and add a ton of immersion
20. Pure crafters - the possibility to just progress through crafting alone adds a lot of options for non-combat characters
21. Emote fights - since these are used in the better RP communities, you don't have to be a veteran uber pvp d00d to fend for yourself (even a businessman can pull a trigger)
22. Realistic RP - this is available in abundance, mature players that are big on immersion and canon, but still leave room for fun
23. Depth - complex crafting procedures make you feel like you're really doing something, and can be good at it too, as well as add realistic feel and diversity, since there are so many options available for everyone, in terms of gear and skill specialization
24. Free trial - 14 days of trying SWG will cost you nothing, no risk, so even if you are skeptical about the RP you could try it on the off chance that it'll be something beautiful
25. Player cities - great for laying down roots and building communities, and taking part in those that already exist
26. Vehicles - cheap single-player and multiplayer vehicles are readily available, so you can take your RP on the road
27. Pets - you can get trained pets that'll fight for you, do tricks, eat and be happy or unhappy, and keep them out as long as you like so you can roleplay petting them and whatever
28. Droids - like pets, only mechanical, and just as cool, with a great deal of actually useful features, depending on what your droid engineer builds into them
29. Mounts - you can ride creatures too, like a bantha if you're a savage or a dewback if you're a stormtrooper, or whatever, and these aren't uber high level stuff either
30. Dice - if you can't OOCly agree on something in RP, you can agree to roll for it
31. Much more - I'm sure I didn't remember everything yet, but it'll come to me, and then I'll sure to share