Tend to agree with Lord Didders, although there is always the Kettle factor
.
Obviously, the 'cost' of a mistake by a ref is greater than it was, so owners and managers are now often the first to criticise refs. Especially Premier League refs. The media even have retired refs critiquing current refs. So slagging off refs seems to be even more accepted than it ever was.
In addition, players are now much more likely to cheat, including play acting to get their 'fellow' professionals sent off. In days gone by, the same end was achieved by hacking down an attacking opponent (usually by a half-back, put in the team for the very purpose). On the whole, such blatant hackers have been purged from professional football, but refs now have to deal with all sorts of less obvious fouls.