India as a country

Is the idea of India as a nation fundamentally flawed? We often highlight our cultural diversity as a strength, but in reality, it can sometimes act as a barrier to efficiency and cohesion. For instance, as a Tamilian, I share more in common with another Tamilian from Sri Lanka than with someone from Punjab or Bengal. Likewise, Punjabis may relate more to those in Punjabis in Pakistan, and Bengalis to those in Bangladesh, than to people from other regions of India. Given this, wouldn't it be more practical to structure nations along cultural and linguistic lines for better governance? While we do share a common history, is that alone enough to sustain national unity? My intention is not to start a fight, but to have a genuine conversation, because after all I too am proud to be an Indian