Ad too few tickets: I happen to live close by the venue (CCH in Hamburg) they fill up. And they do fill it up. That is the limiting factor.
Some person that wanted to get a ticket not getting one is bad, but what is worse is to have more visitors than you or the venue can safely handle. This and of course you still want it to work for the type of event you're doing, with multiple stages, parallel talks, ideally minimum walking distances, not a lot of extra tech to rent in terms of projection, sound etc.
To my knowledge the 3C congresses have been a story of growth and having to move to the next-bigger venue throughout the years.
Some person that wanted to get a ticket not getting one is bad, but what is worse is to have more visitors than you or the venue can safely handle. This and of course you still want it to work for the type of event you're doing, with multiple stages, parallel talks, ideally minimum walking distances, not a lot of extra tech to rent in terms of projection, sound etc.
To my knowledge the 3C congresses have been a story of growth and having to move to the next-bigger venue throughout the years.