I have been thinking along a very different line.
Let's analysis in a cold, calm, logical way, unperturbed by the loss of human lives first.
What is a terrorist organisation and what is a territorist?
A terrorist organisation is, stripped down to barebone essential, an organisation of people who use force against the state to acheive their political goals, and a terrorist is a member of such an organisation.
Now if this group of people, usually a very very small minority, use force to get their way over what is usually irreconciliable difference with the state, is it possibly that they be required to attack or fight only the regimental forces of the state, even if they wanted to?
Can anyone imagine the outcome if they were only to attack the police, the army, the navy - the armed forces? Their chances of success will be very dismal and they are likely to be hunted down and locked away in no time at all.
Such a small group of people, to have any chance of success at all against the state, have to resort to a heavy element of surprise and attack where it is most vulnerable - usually the civilians.
Therefore subject to their relative strength vis a vise the state, it is a corollary imperative that "terrorists" do attack civilians.
Labelling them as "territorists" is no more than telling a scorpion that it is wrong to sting and therefore it must be punished for it when the sting is the only offence and defence mechanism it has.
The labelling also shows how our language has been clobbered and raped to satisfy the goals of the authority. For to criminalise the sting is merely (and this relates to Art's point) adding more draconian penalties to the charges of which a "terrorist" will have been charged anyway under the legal system, such as manslaughter, murder, destruction of property etc.
Such criminalisation also deflects from our consideration the demands of the "terrorists" and whether there is any merits in their demands. Another testimony to the fact that the state has the monopoly of force.
Whether or not their case has merit is rather subjective. They may very well consider their case to have merit and the authorities may think that their case is bunk. If their case has merit then they are supposed to be able to take it before the authorities to be dealt with. If the authorities wont deal with it then they have the option of political campaigning. If neither of these things gets them very far then I'd have to say that regardless of what ever merit their cause has no one who matters in their judgement will agree with them.
It's generally considered unethical to kill people except for the purpose of self preservation when ones life is in direct threat by said people. I think that a terrorist would have a hard time making anyone believe that he was holding off emenant threat to his life by blowing up several civilians regardless of the merit of his case either.
As far as adding the 'charge of terrorism' goes I don't see the problem with it. The punishment should fit the crime. It's one thing to do something illegal in the heat of the moment or just because it 'sounded like a good idea at the time'. It's something else entirely to commit a crime because you genuinely think that it is a viable means of political change, meaning that more than likely you will continue even after arrest so a heavier punishment may serve to better deter you. They do the same thing with any form of organized crime.