Why does the weaker skater(s)/star(s) get tougher rountine than the more stonger skater

The weaker skater(s) seam to me to get the more complex rountines why do the people training them i.e Torvill and Dean keep giving them the complex rountine

Some routines seemed a little inappropriate, rather than complicated, for a couple of the weaker ones: making Tana do sexy and Jeremy rocky were intersting choices.

It does seem silly sometimes. They make the routines more difficult for the higher ability celebrities, so really they should do likewise for the lower ability celebrities. And they do do that, but not always.

Jeremy, for example, obviously had problems with speed, so it would have made more sense to give him a slower song. Obviously they have to challenge them and give them something different, but they could have built up to it more.

I also think you have to bare in mind that a stronger skater can make something look easier, like a ray or a suzanne were making really technical and intricate stuff look like a stroll in the park whereas someone who is weaker will make a meal out of something that is a lot easier.
With the music choice they try to even it up, if you do something fast one week you do a slow one the next. They can't just keep giving people slow ones because that is what they are good at, winning the show requires that you are good a various things. Also it is a competition, so they cant just give weaker skaters a very easy routine and better ones a really difficult one. They like to push them and pitch things at one level above their comfort zone. They tend to get it about right most of the time.