Well off the top of the head its because it's large. The company funds will be stuck at one place and a big chunk of it too. This will affect cash flows and the balance sheets of the company.

Large scale investments also have the tendency to have longer payback periods. ( i.e Building a hotels) So when the investment reaches its break even point it may be that it requires further investment to bring it back to par with the competitors in the market. Hence further investment that increases payback periods furthermore.

Mostly, how it's going to be financed .. since that has all sorts of Tax implications and if they are not careful, an adverse effect on their profits (and thus their share price)