One of Hashem's names is El-Shaddai (please pronounce this out loud as "Kel-Shakkai", out of respect). The aggadata says this is the Name Hashem goes by to indicate something that is very nogeah to your question.
Shaddai is composed of "sha" and "dai". "Sha" means "that" and "dai" means "enough". The gemara in Chagiga 12a says Hashem is called El-Shaddai because when He created the world (as El, as God) He was:
מי שאמר די לעולמו
He who said "enough" to His world
What was enough? Rabbi Tovia Singer has a great explanation on this. He doesn't quote his sources, but it is based on the general kabbalistic idea of tzimtzum, the purpose of which was so that there could be a space where we could have free will. Rabbi Tovia explains that Hashem created a physical world over 6 days, and each day He became more hidden. As the world became more and more "reasonable", so did it become more and more possible to attribute its creation to "accident", rather than Hashem's handiwork (May He be blessed). Hashem calculated the exact point at which the threshold would be crossed beyond the point of no return (beyond which, we would never discover God), and yelled "Dai!".
He stopped creating at the exact moment when free will is optimal: any more and we'd never discover Him, any less and we'd be screaming "Kadosh Kadosh Kadosh" 24/7 like angels.
The reason this is connected to tzimtzum is because of the following kabbalistic explanation, which is given over, for example, by Rav Manis Friedman in this great video. Hashem's Ohr Ein Sof is often described (l'mashal) as His Infinite Ratzon (and effectively to us, that is what it is). His Infinite Ratzon is for us to be totally independent, who choose to follow His ways and choose out of our own free will to love Him and attach to Him, and invite Him into our lives, and engage in a real relationship with Him. He doesn't want holy robots, He has angels for that. The problem with Infinite Will is that it can ruin that! Ask any father who tried REALLY REALLY hard to turn his children in to learners. By having such a strong, in-your-face ratzon, one destroys the child's chances of becoming what one wants him to be. Either the child will become a learner but only as a response to his father's ratzon ratzon, under extreme coercion (and therefore it's not him who is doing it at all), or he will be put off completely.
Hashem, l'havdil, solved a similar problem with tzimtzum. He took His Infinite Ratzon, and concealed it, just the exact right amount (for additional reading, look up the kabbalistic concept of reshima) so that we would have the "room" to be ourselves, and come to a genuine lishma service of Hashem. There is of course more to it than that, but this will suffice for the question.
As the Rambam stresses over and over, miracles are not the ideal! Any detraction from a "pure" system of free will is something Hashem wants to avoid (which is part of the reason why it is forbidden to rely on miracles). He wants to give us the "very best good" after-all (see Derech Hashem 1:2:1 for example), and any unnecessary "leg up" He gives us is going to detract from that. In Mishneh Torah, Yesodai Hatora 8:1, the Rambam strongly explains how a miracle is not meant to be there to enhance our belief in God.
If we continue this line of thought, Purim represented the beginning of the Jewish nation's full maturity, to escape the "miracle" system as part of our relationship with Hashem, and get a chance to engage in a relationship with Him without miracles, which is the ideal (or one can say we descended to the level where miracles would get in the way of serving Hashem wholeheartedly). The Chanuka oil marked the last obvious miracle, the last time Hashem held our hand before our big journey and mission into Galut, and ever since then, we have been plunged into a world of ceaselessly normal nature. As Jews, according to the Rambam, our job is to still see Hashem everywhere, in everything. Our job is to realise the true signs of Him, His love, and His greatness, which don't need no miracles to prove!
See my answer here for more elaboration on this concept.
Final take-away. I've often heard it from Rabbi Manis Friedman, quoting the Lubavitcher Rebbe, that the fact that Hashem only spoke to us once, 3000 years ago, is a huge compliment to us. He imagines the angels sometimes coming to Hashem and asking Him the same question you asked. "Nu, come on, you haven't spoken to them for ages, why not say hi, give a little update, a little chizuk?", and, to our great compliment, Hashem turns to them and says "they got it, they got it, don't worry, they'll do a stellar job, you'll see".
We can do it, trust in yidden, trust in Hashem's confidence in us, and His calculations. We don't need miracles, we will succeed without them. Just watch!