Quote from Divide;1212536:
Whoa whoa hold up. You get thunder, ice spear and fireball with the Ace/Hero Card? Does it work on existing characters?
It does not work on existing characters. Ace cards only give you the novice ranks of Hero skills. Hero cards give you mid to high ranks in their related talent skills, but can only be used to make a new character.
@OP: Leveling gets faster as you get stronger. And of course, improving your talents gives you access to a higher difficulty with better gold/item/exp rewards. Be patient. 70-75 for you will eventually become 110-120. Are you also doing exploration levels? Because those would help you immensely early on as they're easier to come by. And are you a freebirther or a weekly rebirther? Do you have your transformations? Have you completed Generation 13? Avon is the place where you do MA (requiring the Avon Feather to teleport to Avon). Of course, at your current strength you might find MA to be more than a bit much currently.
Ace cards will only be worthwhile if you can take advantage of their benefits with a decent leveling speed or an overabundance of AP. Aside from that, their only real benefit is cutting out the middleman for acquiring the skills associated with a specific Hero Talent.
Hero/Elite Hero cards are a decent start-up but they're less for a fresh start and more for bored veterans who can already supply the new characters with decent gear. As you said yourself, the major downside is all the other skills you would have to re-rank on that new character in exchange for only a small handful of decently ranked skills.
Are Ace/Hero cards worth it for your current situation? I'd say no. Instead, endure alchemy for awhile longer to gather AP you would otherwise use for branching into a new skillset. Between base/expl. levels, saga dailies and AP events, the next base 500 levels would very much give you the ability to switch it up without starting over. If you try to start fresh now, you'll only end up feeling the same way with the new skillset when you realize all the skills you're missing from your current main that you took for granted.