S. R. Faruqi:

If this verse is considered to be a part of Mir's view of poetry (and there's no reason for it not to be so considered), then a number of interesting points present themselves:

1) A verse is only/emphatically one that would be based on the contemporary world and contemporary ideas;

2) That is, with the passage of time a verse's meaningfulness or its relevance can become less.

3) If such is not the case, then at the very minimum only those verses from earlier times are real 'verses', that would be meaningful today as well.

4) It's not proper to be so absorbed in the verses of earlier times that contemporary poetry would be overlooked.

5) Earlier connoisseurs may have said anything whatsoever (that is, they may have been supporters of any opinion), but the truth is that every age has its own tone and practices, and if some poetry is alien to the tone and practices of its own time, then it is not appropriate.

6) The sayings of earlier connoisseurs cannot be particularly authoritative in understanding and evaluating contemporary poetry; earlier people have said whatever they've said, but it's not necessary for every idea of theirs to be accepted as unquestionable truth.

Even if this verse would not be taken as part of Mir's poetics, it can still be said that possibly someone might have objected to Mir's verses because he had deviated from the style of the Persian elders; and in answer to that Mir might have said that the ideas of earlier people have passed away along with them, now it's my era, as he says in the second divan:

{897,6}.

That is, another point can be that what's the benefit of speaking about earlier people, or of reciting and listening to their poetry-- the idea that's useful is the one that's being said today. The Russian Futurist poets too were saying something very similar.

Ghalib has [in Persian] given this theme a psychological dimension and greatly advanced it:

'Oh you who are absorbed in the verse of earlier poets,
Don't reject Ghalib, who is in your own time.'

FWP:

SETS == POETRY
MOTIFS
NAMES
TERMS

The flexibility of baat is on fine display here (see the definition above). With such a short meter and such simple vocabulary, the verse has all sorts of possible readings, as SRF notes.

For what exactly is an ab kii baat , literally an 'of-now' baat ? Is it something that's never been said before? Is it something that was said by earlier poets, but that is now of interest only because it's been taken up and claimed by some contemporary poet? Or is it something that is already part of the current zeitgeist, and thus ought to receive poetic expression?

Or does baat refer to a poem or an utterance, so that we're being enjoined to recite the verses not of the early ustads, but of our contemporaries? Or does it refer to an 'account, tale', or even to 'gossip', so that we're being enjoined not to become generally absorbed in the past at the expense of the present? As so often, we're left to decide for ourselves.