ABC doing well or not well prior to the purchase doesn't justify the business model. It just justifies or doesn't justify the price.
The key is how it will be run going forward, and as we saw, the answer was not well.
Now, with Fox, a truckload of dough has been flushed, and the business model is still unproven at best.
Which brings us back to the original problem... Does it make sense to invest in unproven business models AT THE EXPENSE of proven models...
Its not like the parks were getting all the funds they needed to remain current and vibrant... The Fox investment came at the expense of updates to Epcot, and expansions and improvements in AK and DCA. Throw DLParis into the mix as well, and maybe another family film or two per year, or in-house CGI animation...
Now, the model for ABC Family has been changed, and more money will be needed... ABC itself has made only marginal improvements, and Epcot, AK and DCA are all in need of significant investment (certainly more than one attraction each). How will MGM be doing in 4-5 years, if no major additions come its way?