Charity might seem like a win-win, but there are opportunity costs. Fundraising involves volunteer time, and sometimes money, which could otherwise be spent on awards, food, fans, guests, etc… - things which often relate more directly to the enjoyment of attendees, and the celebration and development of furry-related arts and crafts.
While charity events can be entertaining, particularly when live animals are involved, there are often trade-offs - for example, giving a table in a crowded dealer's room leaves one fewer table for others, and perhaps a loss in funding; running an event takes volunteers and room slots. Likewise, while it's not a zero-sum game, many attendees have limited funds, and encouraging them to donate may lower artists' revenues.
This all needs to be be justified - and the way to do it is to include the organizers' charitable goals as part of the event's mission, as stated within its organizing document or bylaws. These statements don't have to be super-specific, just 'part of the purpose of this organization is to help raise funds for other non-profit organizations in the areas of X and Y'.
Documenting the nature of an event's charitable commitment provides clarity to organizers, who are often faced with difficult decisions about resource allocation - e.g. do we save this surplus for future year's events, or give it to charity? (I've seen this play out at a board meeting.)
Organizers may also determine that charitable activities are not going to be part of their core mission. This is good to know, as it can lead to a frank discussion of what is permitted, resulting in more-specific policies - e.g. "each staff member may spend up to 1/8th of their required work hours on charity-related events" or "1/10th of staff positions may be dedicated to charity". (That doesn't mean that staff can't spend more time on charity as individuals; just that the convention's members aren't going to pay for it.)
The formal nature of an organization can hint at whether charity should be considered a key part of its operations. For example, Anthrocon is a non-profit social/recreational club (501(c)(7)), with the "sole purpose of [operating] a yearly convention in order to bring together devotees of anthropomorphics from near and far, in a relaxed social atmosphere where fans of all ages may feel welcome [… and is] dedicated to keeping its cost of attendance to a minimum." You wouldn't expect such an organization to be focused around fundraising.
In comparison, Midwest FurFest's Midwest Furry Fandom and Further Confusion's Anthropomorphic Arts and Education are charitable organizations (501(c)(3)); both have support of animal-related events written into their public mission statements (MFF, FC/AAE), albeit as secondary goals. When attending these events, you might reasonably expect a portion of your membership fee to go directly towards charitable goals - or at least to see significant fundraising activities.
Tax-exemption issues aside, neither approach is objectively "better" from a governance perspective; what matters is adherence to the mission. For example, Anthrocon does in fact raise significant amounts for charity - through a variety of entertaining social events - but if it started giving away large chunks of its own money, it'd be reasonable to ask why the membership fee was not reduced instead. Conversely, MFF regularly helps to raise large sums and donates directly to its sponsored charities; if it scaled back its support, there'd be questions to ask.
[There might, of course, be good answers in both cases, such as "large donations improve the guests we can attract" or "we bought art panels this year" - but there should be some reasoned justification based on the organization's mission.]
In conclusion: if an organization you're involved with is spending significant time and money on activities outside its documented mission, you should ask why… and if you're running it, you should fix that, either by scaling back these activities, or including them within your organization's formal mission.
This doesn't just apply to charity, of course; but it's particularly easy to get wrapped up in "doing good deeds" and forget that an event is meant to be serving the interests of furry fans, not our furry friends - or alternatively, to let your charitable activities languish, while claiming it's still an important part of your mission.
With the proper mission wording in place, and a practice of evaluating ongoing activities against it, staff can make better decisions - and organizers can be more confident that, when they move on, their original goals will endure.
I wrote this post after a brief comment by tfbaxxter on NordicFuzzCon 2015 (a great con, by the way!), but I've been interested in charitable activities at conventions for years - this was just a good opportunity to write about it.