Making a Will is not about wealth it is about making sure that what you want to happen to your estate does happen. It gives you the opportunity to specify such things as who will administer your estate, who will care for your children and who will receive specific items of your property.
With professionally drawn wills a lot depends on the individual style, of the draftsman. The important thing is that the terms used are unambiguous so as to avoid costly disputes after your death. There is also no requirement for a will to be written on any special type of paper.
For example, the London Probate Registry has a will written on an egg. However, it is not recommended that you adopt the procedure of writing on anything other than paper or see http://www.itc.co.uk/howtomakeawill
Sometimes they omit essential matters such as the appointment of executors or write conflicting dispositions of their assets.
Others simply fail to comply with the formalities of execution. I have dealt with one case where the testator wrote out the will in good style and had it witnessed by two witnesses.
Unfortunately, he completely forgot to sign it himself so, as far as the law was concerned, it was of no more consequence than his shopping list.