The short answer: he plays much too safe.
Interviewing Sachin Tendulkar questions your journalistic ethics almost as much as writing a hotel review after a three-night-four-day-all-inclusive free stay does.
You only ask questions his PR has approved prior to the interview - his answers, therefore, stick to the script. You are denied an interview if you show an interest in his opinion on topics that are vaguely controversial. He's committed to silence on match fixing when it first exploded (made one statement eleven years later to a South African news channel); on BCCI's allocation of money for other sports; and even on the all the controversies surrounding the IPL and CPL, he like other sportsmen, chose to stick to his job. His only contribution was to suggest splitting one day matches to a two-innings format.
He has also been silent on issues that directly concern him as well: His asking government to waive the appropriate customs duty for his gifted Ferrari (that he subsequently sold for an undisclosed amount); his claim to be a model to get tax exemptions for his income from brand endorsements; and the more trivial issue of his attempts to bypass regulatory authorities to build a gym and a swimming pool in his house.
So the questions you hear or read about are limited to: Who's the toughest bowler? Where was your favorite tour? When are you retiring? And is Boost really the secret to your energy? In other words, his opinions aren't just limited to cricket, but to him and his cricket.
And therein lies the problem. One can't fault Mr. Tendulkar for being a public figure and restricting his opinions and press statements. That is his prerogative and if I were him, I'd do the same. But the Rajya Sabha is meant for debate and discussion. And, theoretically at least, a place where one is enabled with powers to act and influence. Mr. Tendulkar is far too quiet. He doesn't commit to any conversation, never takes a side and contributes nothing to a larger topic of discussion.
Look at public figures at the other end of the spectrum such as Shah Rukh Khan and Aamir Khan. These are superstars who have taken a stand and gone out of their way to lend their public face for things they believe in.
Aamir Khan is the best example. He has spoken about the country's water issues, supported the India Against Corruption movement and has provided aid and support to several educational ventures. You can agree or disagree with these causes but Mr. Khan, whose career depends on his fan following, won't hesitate to take a stand.
On a recent visit to Leh, I was happy to learn that Mr. Khan had donated a sizable amount of money to restore a school that was damaged by a cloudburst in the region. This is the school filmed in the last few scenes of 3 Idiots - it's now colloquially called, Rancho ka School. His soon-to-be-launched show, Satyameva Jayate, is series where his celebrity will shed light on stories that he believes need to be told. One can argue that Mr. Khan is stepping into the shoes of a journalist and that the show might lack some amount of thoroughness in fact checking that editorial experience brings, but that's deviating from the fact that Mr. Khan is using his public persona to do things other than act, make films and endorse brands.
Shah Rukh Khan is another public figure who's often happy to take a stand. After the attacks in Mumbai, for example, Shah Rukh Khan gave a very strong interview to NDTV's Barkha Dutt. This was not only an important interview for him to do as a youth icon, but as a modern moderate Muslim living in Mumbai. Amitabh Bachchan too, is frequently voicing his opinion on topics of national interest on Twitter. But you'll never hear Mr. Tendulkar offer his views.
This doesn't make any of these actors better qualified to be members of the Rajya Sabha. But these are public figures who you can bet your last dollar, will contribute to discussion, who have an opinion and generally, aren't afraid to voice it.
As Indians we all love and respect Mr. Tendulkar for the pride he has given us, for the runs he has scored, the records he has put in India's kitty and the inspiration he has been for young batsmen around the world.
But he has done absolutely nothing that shows he can lead a nation. He's even proven himself as an unsuccessful team captain. He isn't transparent, he's politically correct and uncontroversial, enjoys unconditional love and support from the entire country and shudders from engaging in any important, controversial and complicated topics of importance. And that's the last thing we need in politics - another public figure who plays it safe and refuses to take a stand.
So please, give him a Bharat Ratna, a postage stamp, a few roads in his name maybe even a few stadiums. Let him continue to inspire cricketers and focus on adding value to the sport of cricket -- what he's best at. But honoring him with an RS membership is making the RS even less effective than it already is.