Some hotels are family-friendly. That is, they have a swimming pool, perhaps an arcade, a playground, things for children to enjoy. Others may not be so child-friendly, but all hotels have other guests who expect your children to behave during their stay.
If you have a child involved in travel sports such as hockey, basketball or football, you know that you spend a lot of time in hotels. There are games, there are tournaments and probably the whole team (if not several teams) are all housed in the same hotel. That is for many children. It is great because you are dealing with the other parents, the children can hang out with their friends and teammates, but there are limits to what the children can do in and around the hotel.
For example: no other guests appreciate a gang of children running through corridors that laugh at their lungs. If you do not let your children run around at home, why do they do it in a hotel? Another thing that fires other guests is that the silent times are not maintained. Just because you are not at home does not mean that you can act at any time of the day or night.
Being in a hotel is a freedom, parents can go to the restaurant or bar while the children are in the pool, but this is also difficult because children must always be supervised around the water, regardless of their age. Even if parents pool in turns, it is better than no supervision at all. Ideally, the children should behave well in the pool which means that they should not run, dive into shallow water and observe the rules of the pool. The same applies to the gym or fitness center if the hotel has one. This is for all guests to use and if your child has a legitimate reason to be there, under supervision, then that's great, but having a bunch of children hanging out in the gym and annoying other guests is a no.
For the most part, children and hotels are a great mix, and families keep in mind the rules, the children are polite and calm and everything is good, it is when they are allowed to run around in the area that the problems are occurring. Nobody wants to be the one who gets kicked out of a hotel, so keep the rules for fun for everyone.