The process of elections in India being what it is, people often get confused between percentage of seats and percentage of votes. Although the Congress and BJP have together managed to gather more seats than in 2004, their share of votes hasn't gone up. Yogendra Yadav explains in The Hindu:
A national trend does not mean a trend in favour of national parties. The combined seat share of the Congress and the BJP has increased from 283 last time to 321, roughly the same the two parties had in 1998. But there is no sharp increase in their vote share. In 2004, the Congress and the BJP together polled 48.7 per cent of the total vote. According to the provisional figures available, the combined share of the big two parties is about the same: 48.9 per cent. Therefore, it is incorrect to suggest that the result signals a return to a time when national parties dominated.So with a mere 0.4% increase in vote-share compared to the 2004 elections (from 48.7% to 48.9%), the two so-called 'national parties' - Congress and BJP - have gained 13.43% more seats (from 283 to 321). Hence, although 51.1% of India rejected 'national parties', these parties ended up taking 59.1% of the available 543 seats.
How is this possible?
For those who find this confusing, here's an explanation of how this is possible: since the election is a 'first past the post' system, it is actually possible for parties to add seats to their kitty even if their vote-share reduces. All you need is an increased fragmentation of votes.
So, since there is no increase in the vote-share of 'national parties', an increase in the total number of seats only points to an increased fragmentation. This election has seen a considerable increase in the number of state-parties (called 'regional parties' by some), thereby proving beyond doubt that there is an increase in political ambitions at the state level. At the same time, there is no increase in political ambitions at the India-level (since the number of so-called 'national parties' has not increased; it remains two).
The Congress rode on the back of state-parties
The Congress has been able to add more seats to its kitty because of sufficient fragmentation of votes in Andhra Pradesh, Maharashtra and Tamil Nadu due to Praja Rajyam, Maharashtra Navnirman Sena and Desiya Murpokku Dravida Kazhagam (all three state-parties and new entrants this year). At the same time, the Congress has benefited from aligning with the Trina Mool Congress and the Dravida Munnetra Kazhagam (both state-parties) in West Bengal and Tamil Nadu, respectively. So it was really a mix of divide and rule and unite-with and rule which enabled the Congress to win. One also recalls that both were practised by the British when they were ruling this part of the world.
When one takes into account the above facts, it should become sufficiently clear that India continues to reject 'national parties'. At the time of writing, 51.1% of India rejects them left, right and center. So much for claims of the 'emergence of national parties' and so much for claims that the "elimination of regional parties from national space has begun".
On the contrary, what has begun is the emergence of state-parties in the national space. The ones which are worth writing home about, we mean (unlike the JD(S)). It is because of these state-parties that 'national parties' are winning without winning. This, too, shall pass.