No, they shouldn't stop suspending accounts. The majority of suspended accounts are done rightfully, but it IS a drag that some are wrongfully suspended.
If you've only appealed once or twice, do it again. Do it every day (politely) for a week or more. We don't know who is manning the appeal email address, how often it's checked, or how backed up it is.
Also, Yahoo Customer Care recently posted this phone number on their Facebook Page 1-800-300-8514 (which a reverse looked showed to belong to Verizon, the company that owns Yahoo), so it might be worth a call just to see if you get any result or at least a useful email address to contact about your appeal. Remember to get an account un-suspended you either need to prove it was wrongfully suspended or that you are a quality user, mistakenly broke the rules, and be able to convince they you'll behave appropriately in the future (might not work, but sure won't hurt if it means that much to you to get the suspended account back).