Do you think that they actually did such things? (Meaning that they did them in such a way that any person who was there at that time could see them performing these miracles.)
Or do you feel that these are just fables which were later added to their biographies by adoring disciples?
Also, if you show off your magic powers, that's why people will be interested in the Dharma, not for lasting or beneficial reasons. They may even write off Buddhism entirely as a religion of tricks. Quite a few Westerners have magic powers you know. I once saw one cut a woman in half! Another made items disappear, only to summon again them at will.
http://www.accesstoinsight.org/tipitaka ... .than.html
"And what is the miracle of psychic power? There is the case where a monk wields manifold psychic powers. Having been one he becomes many; having been many he becomes one. He appears. He vanishes. He goes unimpeded through walls, ramparts, and mountains as if through space. He dives in and out of the earth as if it were water. He walks on water without sinking as if it were dry land. Sitting cross-legged he flies through the air like a winged bird. With his hand he touches and strokes even the sun and moon, so mighty and powerful. He exercises influence with his body even as far as the Brahma worlds.
"Then someone who has faith and conviction in him sees him wielding manifold psychic powers... exercising influence with his body even as far as the Brahma worlds. He reports this to someone who has no faith and no conviction, telling him, 'Isn't it awesome. Isn't it astounding, how great the power, how great the prowess of this contemplative. Just now I saw him wielding manifold psychic powers... exercising influence with his body even as far as the Brahma worlds.'
"Then the person without faith, without conviction, would say to the person with faith and with conviction: 'Sir, there is a charm called the Gandhari charm by which the monk wielded manifold psychic powers... exercising influence with his body even as far as the Brahma worlds.' What do you think, Kevatta — isn't that what the man without faith, without conviction, would say to the man with faith and with conviction?"
"Yes, lord, that's just what he would say."
"Seeing this drawback to the miracle of psychic power, Kevatta, I feel horrified, humiliated, and disgusted with the miracle of psychic power.
"Neu-sur-ba said: You must see any affliction as an enemy and attack it as soon as it arises in your mind. Otherwise, if you acquiesce when it first appears, and then nurture it with improper thoughts, you will have no way to defeat it, and it will conquer you in the end.”
-Lam Rim Chen Mo eng v01 pg. 348 tib pg. 275