Hi @nbt, @funfun, @abhimaan,
The "Why would you like to immigrate to Prince Edward Island?" field is a free-text field which means you can type as many lines of paragraphs as you want. You will notice when you go past the third line of texts, a scrollbar will appear on the right side. The visa officer will just read through all your inputs by scrolling up and down.
I submitted an EOI form and nothing else.
Aside from the consideration of the NOC code, applicants must really write up a good essay to get great chances. I'd suggest to research about PEI, highlight the things that you admire about the place and relate that to you. Things to ponder like how can you help to build the economy, how easily can you integrate and establish yourself, why are you a great match with the province. (e.g. IT is flourishing in PEI and that you would be a strong asset to strengthen the industry in the province.)