VAT is not really all that complicated and accounts for around 15% of the UK tax take. Moving that to income tax would mean a substantial redistribution from working people to pensioners and incentivise moving more production abroad.
Import taxes are pretty complicated but unilaterally removing them would mean we would have nothing to negotiate tariff free access to foreign markets.
Vat is stupidly complex. Try doing an international conference for example. Not to mention the impact on imports as the OP discovered.
Quite why people think tax stays in one place is beyond me - all costs are passed on and tax is no different. Putting the tax on employer NiCS for example would result in roughly the same business collection and payment, but with a significant reduction in administration and the tax gap since PAYE collection is more efficient.
And quite why obtaining foreign items more expensive is seen as a negotiating point could only be brought up by somebody who hasn’t thought through how floating exchange rates work. We want more stuff coming in and less going out. That’s how you win in international trade. Exports are a cost remember.
As we see from the US, it is the local population that pays the cost of import tariffs and taxes. The currency exchange rate fixes the rest.