Indeed. It's worth making one small purchase, or a one-month sub, or an xp purchase to get preferred status- that immediately gives you all the toolbars you'll ever need and raises your currency max to something usable. Considering you get the whole base game for free, I didn't begrudge making a small buy like that.
Beyond the toolbars there's not much you actually need. Just pick up a few things being resold for credits on the open market to make everything else easier. You can normally pick up things like inventory modules with not much hassle. Artifact authorization, which allowed you to wear the top quality gear for your level, used to be a hassle as it is pricey to buy, but you don't need purple gear through the story and all purple gear over level 50 doesn't need the authorization any more, so nvm that.
I bought a bunch of extra inventory space, extra craft slots for some of my characters and two extra character slots so I could play all 8 classes, all just from money I made playing the game and selling some stuff on the market. Really ended up being no big deal at all.
(Silly as it sounds, you may want to buy the option to hide your head slot. The thing is, you do look bloody stupid with a lot of the helmet options on. It doesn't cost many cartel coins to buy off, but people reselling it for credits on the open market know it is in high demand so jack the price up- so it's often simpler just to pay that one off in real money- and it gets you Preferred status if you didn't do it another way).
So what does that leave you lacking?
- Slower levelling speed. Non-subs don't get access to the sub xp bonus, rested xp or the 12x xp you get now for doing class story missions. However, they are getting xp at the same rate at game release- it was sped up for subs, not slowed for F2P,, so if you are generally playing through there is always enough xp (it's only an issue if you are playing through for the sixth time and want to skip bits). Plus the game throws out a lot of xp boosters for free as you complete quests. Plus- part of the upcoming expansion blurb just released says they are going to speed up story levelling even more, as they want the grind out the game
- A limit on how many PvP maps you an play per week. Don't care.
- You can't play Ops, the high-end raid content for 8/16 players. Don't care there either as I'd never get that many friends online at the same time.
- Limited to 3 space missions per week. Space missions were a non-starter anyway so you'll never miss it.
- Subs get bonus coins per month, but you can buy all that with credits anyway (plus remember if you sub for a month and get an authenticator, you'll get some free coins monthly forever anyway)
- F2P guilds have some limits, but that's really minor.
In short, subbing is really for hardcore PvPers/guild raiders and what-not. For the average you and-me player, it functions perfectly well with no sub- and if you do drop a few bits of money here and there (like for hiding the head slot), it's still way less than you would pay for a computer game in general.
I am one of those who was always deeply sceptical about F2P stuff but SWTOR sold me on it- nine tenths of it works just fine. Plus they made more money on this model then they ever did as a sub game. It seemed like the perfect setup to me- the only structural issue is that the game has its grindy bits that clearly had a monthly sub in mind, but as noted above, they have been removing the grind from the game for some time.
Hence me being slightly miffed that this new expansion looks to be sub only right now- we'll see how that works out.