I agree with you that Lady Middleton has not displayed a mean disposition or acted meanly towards the Dashwood ladies like Fanny and that in itself is an improvement in their circumstances. However to date LM has not actually done very much for the Dashwood ladies either. Unlike Fanny, I do not think LM has the temper or interest to interfere with things such as how much rent to charge; this is an issue I think Sir John would consider his decision to make and so far there is nothing to show that he consults his wife on what would often be solely a husband’s, gentleman’s, master’s concern. ;D

Sir John for all his congeniality is not wishy-washy or malleable like John Dashwood and there is also no evidence that LM has the kind of control over her husband that Fanny has over hers; I think there is actually some evidence to the contrary. Sir John shows up at the cottage soon after breakfast the day after the Dashwood ladies arrive but his wife does not, she sends a polite note stating her intention to visit when it is convenient for them—very polite and appropriate I dare say but it is not an extraordinary kindness. I imagine that LM also thought her husband was being uncouth in showing up at the cottage when the new inhabitants cannot be ready for visitors but he does go so I think that may show that she does not have influence in this area and an actual example, in Chapter 7 she shushes him during Marianne’s recital on the pianoforte to no avail. ;D

He said much of his earnest desire of their living in the most sociable terms with his family, and pressed them so cordially to dine at Barton Park every day till they were better settled at home, that, though his entreaties were carried to a point of perseverance beyond civility, they could not give offence. His kindness was not confined to words; for within an hour after he left them, a large basket full of garden stuff and fruit arrived from the park, which was followed before the end of the day by a present of game. He insisted, moreover, [on] conveying all their letters to and from the post for them, and would not be denied the satisfaction of sending them his newspaper every day. (Chapter 6)

Just like LM could not have prevented her husband from going to the cottage too early for visitors or quiet him during the recital, I am not convinced that LM could have prevented Sir John from renting the cottage at a good price to the Dashwoods, or carrying their letters to the post, or giving them his paper every day. Sir John is the one who sends the basket of garden stuff and fruit and also a second present of game to the cottage. It seems to me that Sir John is the author of all good tidings and LM’s contribution is non-interfering polite cold civility. ;D

I agree with Barbara’s interpretation of the Dashwood’s ladies anxiety to see LM and would add some thoughts of my own. I do not see the Dashwood ladies depending on LM for their material comfort. IMO the comfort on which LM can effect has to do with society as she is probably the leading lady in their neighborhood and others will be guided by her treatment of them. I think it might also be that they hoped for an amiable neighbor and perhaps even a woman of intelligence and talent to equal their own and as Barbara has said they are disappointed in this. ;D