I think comparing the development of Rose compared to Martha is a bit unfair really. Rose was always going to have more focus on her, why? because she is the first companion of the new series. To hook the audience in (the majority of whom wouldn't have seen the original series) you need that 'touch stone' character for people to relate too, and Rose was created for that very purpose.
Martha on the other hand, enters when the series is fully established, she has to 'hit the ground running' as it were, because if they spent the same ammount of time showing Martha's reactions to certain situations like they did with Rose it would be a rehash and pretty boring.
The same thing happened in the original series (although fans who talk about 'the Rose Show' would disagree i'm sure), Ian and Barbara were very well developed characters, whilst the Doctor was something of an enigma, and Barbara in particular carried many of the stories in the first two series. However the companions that came after (Steven, Vicki, Dodo *shudders* et all) were pretty 'Cookie cutter' and we didn't get another great companion till Jamie*. In that respect I think RTD has been a lot more sucessful in moving the focus from the companion to the Doctor, but still making the companion(s) fleshed out characters in their own right.
The Tyler clan were definitely better realised than the Jones', but I don't think having a well developed family equates to a well developed character (Ian and Barbara didn't visit their families every 5 minutes) , infact I think it was rather worrying that by the end of series 2 Rose's family were much more likeable and/or well developed than Rose was (IMO)... especially Mickey who is one of the best developed character in NuWho in that he is the only companion who actually became a
better person and stronger character through meeting the doctor (this is a big failing of RTD's: Rose pretty much lost all her humanity, Martha was at her strongest when the doctor
wasn't around, Jack became a better person but then speant 100 years emo-ing after the doctor).
Martha was not badly developed, (it wasn't great either mind you) she at least didn't regress like Rose did in series 2, the 'unrequited love' angle was ill concieved but that wasn't the only aspect of her character. I would say that for me, Martha was a character that was more than the sum of her parts, and that as Time lady says is down to Freema, her presence and her chemistry with David. She reminds me of Sarah Jane in that respect. From watching the old series I'm used to the companion's sucess being all about the actor having to do the best with what they are given, for me Freema/Martha succeded where Bille/Rose failed to in series 2 (and thats not me saying Freema is a better actress than Billie, because I don't think one needs to be a fantastic actress to be a good companion, just a reasonable one who is likeable and has good chemistry with their doctor).
Actually what is interesting watching series 3 back is how much the Doctor trust Martha, he trusts her to work out what to do with the phsycic paper in EoD, he trusts her to hold everything together in HN/FoB, and then of course there is LotTL, Martha saves his life about a billion times: they really were more of a team than Rose and him were and in terms of competency and kick-arseness she really is one of the best companions (only Romana and Ace clearly beat her really). The writers should have ditched the 'unrequited love' bilge and just focussed on that, perhaps having a more tutor/protegée relationship a la Ace/Doctor, with a bit of flirty verbal sparring a la the end of Smith and Jones.
* I always felt as if RTD pretty much based Rose on Jamie and was always trying to recreate the Jamie/two dynamic with Rose (with the added romance of course). He failed

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