Are you a pre-Luther reformer? Then you'll probably want the church to give up wealth and secular power. John Wycliffe complained about the material wealth of the RCC and also thought that it shouldn't have political power over the secular realm. This is because Wycliffe looks back to the early church and says that the current one doesn't look anything like it. Jan Hus does something of the same. He doesn't think that bishops and popes should take up the sword against their enemies, they should be praying for them. He condemns indulgences, and thinks that the church should give up its wealth and live in poverty.

This is at a time when the church owned about 1/3 of the land in Europe, so the question is are the clergy likely to do this? The answer is very few of them if at all. Wycliffe was condemned after his death, and Hus especially was a warning bell to reformers everywhere, as he was promised safe passage to the Council of Constance to help end dissension his views had caused (he had other problematic ideas as well such as giving both bread and wine to communicants), and then was betrayed by Sigismund and burnt. I've heard a couple of historians say that this is the last point at which the RCC could have reformed itself by listening to Catholics. The Council of Constance not only condemns Hus (and Wyliffe), but also introduces Conciliarism through the decree of Sacrosancta, which argues that the council was the final arbiter in religious matters. If you disagreed with the council, then you'd be in trouble, which is exactly what happened to Martin Luther - he was often denounced by his enemies as an anti-conciliarist.

So the question is really about what do you want the church to reform, and does the church recognise it as a problem? Many Catholic humanists were asking for reform, but didn't get it. Much of the Reformation is about who has the authority - the RCC believed it had it, the reformers believed it didn't. Those are mutually exclusive arguments. Perhaps had the RCC not excommunicated Luther, but kept him in the church and kept talking to him, they might have headed it off, but from 1520, Luther started to get much more mouthy about what he now believed to be the truth and that's probably the cascade point.

The Catholic Church did reform, of course, as it always had. It did so at the Council of Trent. Much of the historiography surrounding the Reformation has privileged the Protestant declension narrative, but that is thankfully turning around.

As to whether the Reformation was inevitable: it's hard to speak about histories which did not happen. There was a confluence of things at work: various nobles in Germany and elsewhere were getting tired of Papal interference and Protestantism afforded them a means of breaking off from external authorities (which gave rise to the secular nation-state in the West, cf. Brad Gregory's The Unintended Reformation). Likewise, there was a good deal of laxity in some corners of Catholicism - and this had been noticed both by those who remained Catholic and those who became Protestants (though Hillerbrand says that 'abuses were few and far between' - he's quite right, it's just that what abuses did exist were so obvious and irritating to pious Christians). On top of this was the rise of humanism. Many of the Reformers had been trained in the classics (like Calvin and Melancthon) and thought that the philological and historical tools they had used on someone like Suetonius ought to be applied just as well to the Christian Scriptures. But this was often in the service of evacuating the antecedent dogmatics which governed the reading of Scripture in Catholic theology.

I'd recommend reading Hans Hillerbrand's The Protestant Reformation. Also, on the topic of how the Reformation has been interpreted in historiography, check out Bainton's, "Interpretations of the Reformation," American Historical Review 66 (1960).