I believe guilds should be given the option to ban specific players from joining their guild while maintaining open entry to new members. Changing guild entry from Open to Application is too broad of a treatment when you just want to forbid specific players from joining, especially if said players have been an issue with the guild in the past. Also, potential new members might prefer to apply for Open guilds rather than Application guilds as it requires less time to enter the guild and may appear less intimidating to new players. Plus, it can be time consuming for guild leaders and officers to look at every application and consider who gets in or not.
Speaking from personal experience I’ve seen members leech off guilds and get kicked out when they don’t follow the rules or perform their expected tasks (check-in, Surge, dailies), but then promptly return to the guild and the whole cycle continues. The also applies to members that throw fits, leave, come back, and make more aggressive messages to aggravate guilds.