As I mentioned in case of Bureaucrats, political affluence does have a role, same is in case of Ministers.
UPA was bugged by regional parties and everyone knows, what are criteria used by the regional parties for nominating someone for ministerial post.
Many times they have considered cast/religion/region as criteria.
In case of Smriti Irani, it was her dedication to get task accomplished, seems to be have her positive attributes. Many times we are not ready to get in project, as we are sure that it is failure and may have negative effect on our profile. Here she has taken responsibilities and fought from Chandini Chowk as well as Amethi, were everyone was knowing that she will be defeated; however, it helped BJP by being seen as serious contender and sure of their victory.
Will you like to hire a driver for your children, who is highly qualified and done different certification OR someone who you trust (in driving as well as taking care of your children). There are places where you have to higher/appoint who have qualification & skills; however, Politician needs to be only Strong willed person with logical thinking.
Ministers are driving force of a government and PM always wants to have a team, which can deliver (Provided he has choice). Raja was re-appointed even though Manmohan singh not wanted, it was compulsion and lack of strong will.