You'd be mistaken in your understanding then. Amillennialists and Partial Preterists alike would, on the whole, understand that the world does not get better until the Eschaton; but that things get progressively worse.
Only the Post-millennial view provides a possible framework of cosmic optimism, though not necessarily so. Strictly speaking Postmillennialism simply states that Christ returns after the Millennium, and the Millennium is understood (usually) as a figurative period of time. Amillennialism, by distinction, is focused chiefly on the idea that the Millennium isn't literal, but describes the reality of Christ reigning over all things from His throne in heaven. However in some forms of Post-Millennialism the Millennium is understood in a dominionist framework: Through global missions the influence of the Church grows, and the world progressively becomes more and more Christian, and then at the conclusion of these things Christ returns to take full possession of the kingdom. Amillennialism, on the other hand, confesses that Christ is Lord, and the kingdom of God has nothing to do with temporal authority, but is the objective reality of Christ's Lordship and the Church bears witness to Christ's Lordship--whether the Church is persecuted, tolerated, or in a state of favorability doesn't change any of that: Christ is Lord regardless of whether Diocletian or Theodosius is emperor. In the general Amillennialist view, the world is indeed broken and fallen and while we are called to be salt and light, the reality of the fallen condition of man and the world means things will even at their best still be broken; and often times be quite terrible--and likely to increasingly get worse as time marches forward. The Christian witness in the world never changes, even as the times and seasons change; the Church to be an immoveable rock of faith and hope in a seas of instability, despair, and unbelief. Kingdoms wage war against kingdoms, nations rise up against nations, and this is the way of things right up until Christ returns.
Partial Preterism is not, of itself, its own thing. Partial Preterists are often also Amillennial (or Post-Millennial), but it would not surprise me to also learn that some Partial Preterists are Pre-Millennial. Partial Preterism is, strictly speaking, a framework of dealing with certain key biblical texts which recognize that the focus of these texts is not strictly Eschatological, but rather are about the destruction of Jerusalem and the Temple.
Full Preterism, on the other hand, is its own thing. Believing that the Eschaton and the destruction of Jerusalem and the temple are, effectively one and the same; and that the Parousia refers not to a literal visible return of Christ at the conclusion of history but to a return of Christ in judgment against Jerusalem--and that the resurrection of the dead is not a literal resurrection but effectively just a romantic and poetic way to speak of "going to heaven" after we die. Full Preterism, therefore, doesn't really say whether the world gets better or gets worse; but rather this world ultimately doesn't matter and things will just keep going forever or until the sun blows up or we all destroy ourselves in war or whatever have you. The future of this world is irrelevant in Full Preterism, the physical and material universe will just keep churning along seemingly forever or until the material elements of the physical universe dissolve (i.e. entropy wins in the end). If you ask me, that ranks Full Preterism as the most pessimistic and nihilistic view of all the ones listed. Though I don't hide the fact that I truly dislike Full Preterism because I believe it is a heterodox system that gets the Gospel very, very, very wrong on many very, very, very important issues.
The general Christian view, regardless of eschatological persuasion, is that the present world is broken and hurting and fallen; things are not going to get better, things are going to continue to be bad (and/or get worse) until Christ returns and God sets all things to rights. This is not unique to Pre-Millennialism; though certain forms of Pre-Millennialism may entertain robust speculative narratives about the bleakness of the future. Which do quite well if one is interested in raising the level of fear among the Faithful, or to sell popular fiction using eschatological themes. Fear-mongering can be a very useful tactic if the goal is to manipulate your audience. And no, that isn't exclusive to Pre-Millennialist schools of thought; but Pre-Millennialist schools of thought are full of fear-mongering in the present day. Just take a look at every time the news cycle mentions conflict or war in the Middle East.
-CryptoLutheran
