Of course, the main incentive for a school to become an Academy is financial. The school gets the proportion of funding that might otherwise have gone to the Local Education Authority (LEA) so, if your LEA hitherto took 15% your school gets a 15% increase in finance. But the Academy now has to pay directly for services previously provided by the LEA (payroll, training, advisers, insurance etc) so you need to do your sums carefully. The Academy is also free to drop the National Curriculum, and becomes a 'Publicly Funded Independent School'. (Meanwhile, Michael Gove buggers about with the National Curriculum so that maintained schools won't know whether they are coming or going). So essentially, the policy aims to move schools from the public sector under Local Authorities, to the independent sector - a cynic might term this privatisation by another name.
The justification for this is, of course, ideological but it is claimed that the aim is to 'raise standards'. However, if you were to check OFSTED's recent statistics you would find that 78% of maintained (i.e. LEA schools) have been assessed as 'Good' or 'Outstanding' whereas only 62% of independent schools are assessed as 'Good' or 'Outstanding'. This would suggest that becoming independent is more likely to lower standards.
But no. This is where Michael Gove and his Band of Devious Bastards have worked the trick - you shift the good or outstanding maintained schools into the independent sector and Bingo your ideology is justified as the independent sector shows a rapid raising of standards!