Those are fair questions, and given the clamour amongst the 'arm Ukraine now' crowd, it's important to recognise what the limitations are on weapon supply, system integration, ammunition manufacture etc.
A couple of good things I read recently that explore this fully, but I know people don't want to click through to twitter, so I'll attempt to summarise.
The first from Mark Hertling (retired US general).
Essentially, once administrations realised last year firstly that Ukraine should be helped to win, and secondly that they were capable of it, the question became one of how quickly it was possible not just to send hardware to Ukraine, or even to train people to operate the things, but also to set up and train the logistics, repair, maintenance teams that keep those systems running. Those things take far longer than simply sending tanks or artillery over in large quantities, so the calculation (Hertling argues) is about how quickly they can be done, and staggering the announcements in such a way that takes account of the speed those systems integrated into the Ukrainian army. This staggering of announcements and supply can also come across to some people as 'drip feeding Ukraine just enough to prolong the war'.
The second is the post from
kebabking about ammunition supply:
Ukraine and the Russian invasion, 2022-23
Essentially, political decisions have been made that mean the ready supply of ammunition for Ukraine's offensive is not yet there in such a way that Ukraine won't experience shortfalls in ordnance supply without the extraordinary provision of things like cluster munitions, which are more effective against groupings of enemy soldiers, while needing less ammunition, and also providing the bonus of not wearing out artillery gun barrels as quickly as needing to fire the equivalent amount of normal munitions. It essentially extends the Ukrainian ability to maintain their offensive by an extra few months into the autumn/winter as necessary.
You ask in your post why more substantial direct action can't be taken to help Ukraine win now and quicken the end of the war. By this, I'm guessing you mean things like NATO or its own members individually sending in troops, or at the very least its own maintenance/logistics teams to look after the western systems, while Ukrainian soldiers get on with the business of fighting and dying. That may well end up happening eventually, and
kebabking has covered those possible eventualities above. Those in charge have calculated that staying out of the war directly, and maintaining the staggered supply of weapons to Ukraine is the best way to ensure that Russia's red lines aren't crossed. Time and again though, we've found that things that were originally considered red lines garnered no response from Russia except bluster. Perhaps that will continue to be the case if Ukraine's allies decide to be even more bold in the assistance they decide to offer Ukraine over the next year.
From a moral standpoint, I personally don't see any problem with supporting victims of territorial wars of imperial conquest via means up to and including troops on the ground, in order to save civilian lives from brutal occupation, murder and genocide. I appreciate that the political realities of doing so dictate that this was never a realistic course of action either at the start of the war, or now. Doesn't mean it might not be the case in the future though, depending on whether Russia decides to escalate further, and to what extent Ukraine proves its ability to take back significant amounts of territory over the next five months.