Another difference between political and social reforms is that political reforms have no 'costs' that is, you will not see anything in the negative column in your budget. For these reforms, the player may implement any of the possible choices and is not required to have already implemented some previous reform.
Unlike social reforms, some political reforms are not 'next step' reforms. There are a total of eight political reforms, each ranging in their number of choices. Every reform also gives a bonus to immigrant attraction, though this is unlikely to be of any use unless you're in the new world. Whatever may be the case, political reform is all but inevitable in Victoria 2, especially if you want to stave off Jacobin and Anarcho-Liberal revolts. Or perhaps you wish to roll back reforms, and entrust the reactionary aristocrats with ultimate power. Or maybe you want to ensure that the liberal moneyed classes control policy. Perhaps you want to give greater voice to the socialist underclasses so that you may implement social reforms and plan your economy. If you are aiming for a specific type of government, you may want to implement reforms that will change your current form into something else. There are many reasons to pursue political reforms.