[JeorgeNoxeref]

My speculations from what I understand and have read from others:

1. Perhaps, the character of Mara was just a mere reinforcement to show all what the Buddha had already knew in advance: that the Sangha is stable and fruitful and when all of that is done and fulfilled, it would be the confident time for His Parinibbana?

2. I would not dare to equate Ananda's earlier non appeal to Mara but rather a personification of the Buddha's opponents, those within and without, who are perhaps waiting impatiently for their major obstacle, the Buddha, to go in order for them to take charge or be rid of a 'troublesome barrier'?

3. The timing of Ananda's appeal and the Buddha's rebuke to him was one instance in my estimation of a Dhamma lesson of what happens when one loses the present moment and then lives other moments trying to regain that lost moment, losing the present moment again in that process.

4. Another Dhamma lesson on displaying the inevitable impermanence and death and that His highlighting to Ananda was also is an indirect way of showing what He was capable of as a Buddha and as a final Dhamma lesson?

Other addendum comments:
5. That time to request was over as the Buddha had given that opportunity but it wasn't utilised and that it would not be appropriate for Him to make a ridiculous roundabout turn on one latent whimsical plea when it was of greater importance towards the end of His life to attend to other concerns like the direction of the Sangha and so forth

6. All of what is needed to accomplish has been fulfilled in the Buddha's life, so Mara or not, He already knew that it was the time to relinquish.

7. Just like the Dhamma has to be requested to be taught, perhaps this applies to His lifespan too? That it was 'courtesy' to inform, of all people, Ananda, about it?

8. I have read how some alleged that the Mahaparinibbana Sutta has bits and pieces coming from later development and etc...but as I am no historian nor scholar, my attitude remains within the confines of Kalama Sutta.