James Ohlen gave a talk at GDC 2013
What? They are in the millions on active players?
and reported that since F2P launched, they've had over 2 million new
accounts created. Granted, not all of those are continuing to play, but added to the existing playerbase of subscribers previous to F2P launch (estimates were sub-1 million, say 800,000 or so), I don't think it's unreasonable to think there are around 1.5 million active accounts (combined subs and F2P).
On the subject of achievements, I have to echo the previous posters, though in a less-confrontational manner. The purpose of F2P is to entice you into spending money (that is to get you to subscribe and/or purchase Cartel Market items), not for you to get the entire game for free.
And even as a sub, I can't get all the achievements, because many of them are bugged. My launch character was an Imperial Agent Sniper and I don't have credit for completing Chapter 1 of the Agent story because it requires you to have completed all 4 dialogue arcs at the end of Chapter 1. I don't have credit for killing Jarg & Sorno on any difficulty mode in Karagga's Palace, even though I have credit for the bosses after and have the title for the Speed Run and Nightmare mode. I don't have credit for killing all the bosses previous to the end bosses in about half of the level 50 HM flashpoints because they're bugged.
Not to mention the fact that some of the achievements are for killing quest mobs, which would require me to re-roll to even have a chance at since I don't get retroactive credit. Oh, and the achievement for killing Tythonian Training Droids requires killing 4 more droids than will spawn during that quest series. Oh, and one of the Space Mission achievements requires completing an objective that isn't even in the game. Oh, and the overall achievement for Taris (Republic I believe), requires completing a Heroic mission that was removed before launch.
This is version 0.5 of Achievements in my opinion. It's there, and a lot of it functions, but there are many bugs and impossible achievements.
Personally, I really don't understand the amount of hate SWTOR's F2P system gets. Most games that have any kind of free option position it as a free trial and limit you to a low level. The ones that don't are pure F2P with microtransactions. F2P in SWTOR allows you access to the entire game (though certain things require the purchase of unlocks or passes, which can also be purchased with in-game credits from the GTN).
Last thing I'll say on that matter - you don't like it, don't play it, but don't come on internet forums and badmouth a game that millions of people play and like because you don't wanna shell out the money to reward the developers for the work they put into it.
I've been a sub since launch, and will likely continue to sub for the foreseeable future. I enjoy the game. I like the direction they're going with the game. Of course there are issues; every game has issues. But in recent months I've seen a lot of changes and communication from Bioware suggesting that those issues are being heard (and even addressed/fixed with recent patches).