This was considered, but all it takes currently to attend a quest macro is to keep an eye on your journal. Anti-botting gumps would require you to tab over and interact with the game every so often, while the actual scripters eventually find ways to automate the anti-bot gumps. All in all, this would hurt attended players more.
We have been punishing offenders, and there are people with so many repeated offenses that have had account bans lasting 2+ months.
(That, and of course, their spoils being deleted.)
Unfortunately, the OSI-accurate way is very exploitable, and Demise has always been striving for "OSI, but better". Part of the problem here is that any newly created character can buy a stack of bolts/arrows and start macroing, which is not possible for the bulk order systems unless the BODs are already obtained and completed by a crafter. We believe that increasing the difficulty to macro it unattended for days on end, while increasing the difficulty to complete the quests (at a continuous pace) for everyone equally, is a better situation.
The chance of getting a runic kit from a fletching bag reward is actually quite high when comparing it to getting runics through the bulk order systems, where you would first have to obtain a rare large order, and many large small orders that fit the large order to complete it. Randomness is equally a factor, even though the reward for a certain bulk order is guaranteed.