As Mikey has siad, they will soon find ways of avoiding as much tax as possible and as Buenchico confirms, they have a duty to do so. For as long as there is more than one tax regime in the world big companies will take advantage of those that best suit them
There is nothing "immoral" about reducing one's tax bill to the absolute minimum (whether that is done by a company or an individual). Moving profits offshore is no more immoral than putting one's savings into an ISA. They both avoid tax within the law.
Like it or not the world's customers have big companies to deal with. If you want to sit at home in the dark (because you don't like the "Big Six" energy companies' excessive profits), without using the internet (because of Google trawling your PC), making your own coffee over a wood stove (because you won't use Starbucks), and trudging up and down the High Street among the boarded up shops looking for goods (without being able to stop for a coffee, see above) then that's fine. Personally I like the option to keep all the lights on, surf the net and use Amazon to find the goods which I cannot get elsewhere. I also like to pop down the road for a large Cappuchino when it suits me. I want and expect all the companies that provide those goods and services (some of whom I have shares in) to keep as much of their profits out of the hands of wasteful and profligate politicians. This keeps their prices down, my dividends up and leaves me with more of my own money to spend as I please.