Not every vote is expected to be a one-off setting the policy direction for a generation or three. And whilst it's normal for older people to be more conservative and more reliable voters, the skew by age was unusually strong in this one (56% of 25-49 year olds voted Remain, 75% of the under 25s that actually voted voted Remain, but 56% of over 50s and 61% of those over 65 swung it in favour of Leave)

As for alternatives, I mentioned higher quorums ("If 50% of the entire electorate vote Leave, we'll leave" would have seen no change happen, at least until Cameron was undermined by his own party) which are actually pretty common for major changes in democratic votes within organizations. There were also calls for 16/17 year olds to vote although this certainly wouldn't have affected the end result.

Tangential point for futile rhetorical arguments: the split between net taxpayers vs net recipients of state benefits/pensions which I don't think any pollster has been bold enough to evaluate. Usually pensioners are strongly conservative and the unemployed and unskilled part-time workers strongly left-wing which makes "our voters are the ones paying for it" arguments redundant, but Brexit is one cause that almost certainly united the votes of pensioners and the unemployed and underemployed, and depended on them to prevail