Well, of course, if you have a trade mark and don't use it, you risk losing it. If the law says you can't use it, you probably have good reason which would overcome a non-use challenge, so perhaps that argument doesn't get you very far: and I guess it has happened in the past, with Olympic signs, red cross and red crescent, and even the word ANZAC. Anyway, if you can't use the trade mark what's the point of maintaining it? The tobacco industry has resorted to arguing that the UK's international treaty obligations prevent it from legislating to require standardised packaging, because of the trade marks aspects, which seems to me like grasping at straws.
If people aren't put off buying tobacco products by the health warnings, how likely is it that making the packaging less glamorous is going to stop anyone? A fortiori, how is going to help smokers kick the habit? Even if cigarettes were sold in plain brown cardboard packets I can't imagine it would be much of a deterrent, and the manufacturers would save on manufacturing costs which can't be an intended consequence. The consultation paper raises questions about cross-border shopping (a concept which, helpfully, it explains to readers) and illicit imports (I don't think the word "contraband" is too strong, though the consultation paper doesn't use it), which led me to the idea that standardised packaging would actually help HMRC and brand owners because imported packets would stick out like sore thumbs.
If the government stipulated that health warnings had to be of a certain minimum size, though, they could require a packet of 20 cigarettes to be so large you'd need a van to move it. Now that might be a deterrent. Even so (assuming that brilliant suggestion won't be taken up) I take the view that if standardised packaging stops one person from smoking, it's justified. I just know, however, that no smoker I have ever known would give up so easily. They need more than that to help them to do so.