Yes you actually can,
I hope this makes sense to you, but if story is what you play for, today you can play just the story and be very successful doing so. A few months ago, you would have to grind, but I liked doing that and the fetch quests so, up to you. Now these quests only help level you, and you are not grinding. Just fall in love with crafting and tell your companions what they want to hear. Experience is easier to get today than ever. When my sub lapses, I may have a modified opinion of rate, but as for now, the rate as a sub is fast.
I played preferred for much of the time. I subbed for rewards that felt worthwhile, mainly the Narshada skypalace and when Knights of the Fallen Empire was announced I considered playing more.
Class stories completed rating 1-5
Trooper 3 though this is still my favorite char somehow.
Sith Warrior 5 I hated the guy at the end so much I actually lost sleep just to kill him
Jedi Knight 4 This is very likely what could have been a good single player game and have this resemble Kotor 3, but alas this is MMO
Classes well underway
Bounty Hunter 3
Jedi Sage 3
I am drafting this response, so please ignore incomplete thoughts or spelling errors,
I loved all of those stories, if I played with friends I actually knew in real life, I would play grouped, often the problem is people will rush you through content they have played before. Flashpoints are a good example, people rush you, people often tell you to skip because they have played this already often that day and it gets annoying. You are not playing a single player. The world is filled with other you-s if you are a trooper, for example, look there is another trooper who just killed my mob...... That trooper needs to go away, I am Havoc Squad (lore comment) and guess what that trooper is also in Havoc Squad. Subscriptions relate to credits, experience gains, some group missions, and a lot of chest pounding because they think the yare better. (I was happy either way, call me weird, I don't care.) Obviously though, they do have very real advantages. Though the fun level of the game is not taken from you, you can survive without year subs, some people can't.
Pros as a non sub,
To be honest the game is meant for subscribers, however as a pro I unlocked most of the features I wanted with cartel coins, played content for less, suffered the same internet problems for less than subscribers.
Pros as sub or short time sub
I think you could get away with one 60 day time card to really hammer out some characters or if you play less at one to one and a half. 60 days is a lot of time. If you buy the disk for 15 you get 30 days, another benefit for time cards is amazon prime users can sub for cheaper 27.99 and can use points form amazon prime to reduce the next one you buy. That is if you shop online with reckless abandon on amazon. You have full access to the game, buy as many cartel market items that unlock weekly passes.
So you are a solo player? Cons won't affect you much,
Biggest con for non sub is the credit cap, this is harmful to you if you buy items off the gtn and that creds in the escrow do not come back out. 350,000 is the preferred limit. Which is more than enough as far as I know, I have never spent more than 350,000 creds on a in game merchant. I did off the galactic trade market which other players sell items.
Knights of the Fallen Empire
You should sub at least once to get this, either when you play soon, or when all chapters have been released or most. Buy the disc you get your 30 day sub pass, one 60 day card is 60 days 30+60=90 right? If you subbed today you would be in good shape for KOTFE. You could also wait until you have a level 60 char and then pay for the sub. Time cards are good because they do not take money off your credit card to recurring sub fees, the yare one time buys. Better for finances if you forget. I would rather know the 15 bucks is still there that I did not intend to spend.
Ok so your asking why this looks disjointed, experience is one thing, sub rewards for your story quests are better as a sub, when playing shadow of Revan, sub, better rewards.
Today if you subbed you could get to level 60 on ordmantel which is a 1-12 planet because of the 4.0 update. You can actually finish those fetch quests, (WHICH I LIKED BY THE WAY!) Yeah so I am alone on the fetch quests, that is ok. As for your story, KOTFE is meant for solo players, I played solo, I have never done an op mission, I never needed to, except to finish what is the planet? Oh yeah, oricon! Oricon ends with a ops mission, so for the after 50 content you will have 1 ops you should do, they really didn't impress me when I saw I had to group to finish, so I skipped them. Lore critical? I don't think so. OPs are for subs only, you can pay 5 bucks to get some cartel coins to get a pass or if you work it right every once and a while ops passes are available from other players for creds. They are worth=600k escrow vouchers and ops passes will sell for 500k often. I eventually sold mine back for that price and bought with real money the pass, your time getting that amount of credits is worth something too.