A list of 18 must have and 12 can have school website features - and why you do not need everything.
Most of the must have school website features is "static" information which is displayed by pictures, texts and downloadable files. To this belong:
A news blog to describe in text and show in pictures all the wonderful pupils, teachers and parents and what brilliant things they have done in your school. The more news blog entries you have the more lively your website appears. And the more visitors you will have, since they love news.
Many can have school website features are interactive, which means that you interact with a data system to give or get some information. All this can also be done without data, but sometimes interaction can have an advantage if it is easy to use.
All in all, it is not easy to think of all necessary features for your school website, so it helps to take a rest and make a list of things.
However, to add all the necessary features to your school website is a matter of static features. Everything you really need will be integrated in form of text, pictures and downloadable documents. If you have the money or skills to add more interactive features, you will get to the section of "can have" features. This also means that to create a school website with all the necessary features, you do not have to spend too much money of only 1,500 Euro, this can be done with a simple website builder like Jimdo or simple school website templates with html and css. Thus website building for free is possible and easy, too.
So this is why you do not need all possible features you can buy or create yourself.