Lightroom first shows you the inbuilt preview imbedded in the RAW file. It then loads the default settings which is the change you are seeing. those default setting are based on the data that Thomas Knoll and others at Adobe built. However......
The simple reality is that as Adobe does not have access to the proprietary information of the camera manufacturers it must estimate a starting point by whatever means, be that reverse engineering or just taking a guess. this is the same for all third party Raw converters. You may feel one product is better but it's just you agree with the opinion of the person who made that profile. Others may love the profile you hate. It's just opinion. Even DPP has profiles and offers a choice (landscape, portrait, natural etc) of profile for each camera model. For the record I really dont like what Lightroom/ACR does with colour either. Adobe take a 5D or two (for example) and use the camera and RAW files to make the profile. Those cameras may or may not represent the true average colour for that model and the methodology may or may not get the most pleasing colour. Adobe simply don't have the information to provide more than an informed guess as to what the colour for a particular model should be, and some profiles are better than others.
But DPP doesn't let me make my own profiles. I have to settle for what Canon says the colours should be. I don't want to be the same as every one else. By using the calibrate tab in Lightroom I can make as many camera colour profiles as I want. I can make my own portrait, natural and landscape profiles for each camera I use based on serial number. They don't have to be made using a colorchecker (although I used one as a starting point). You don't have to have reality or accuracy as a colour profile. DPP doesn't do it and I know of no film that ever had perfectly accurate colours. If we all wanted accurate there'd be no Velvia. Go and make a profile you like using the calibrate tab and set that as your default.
So it is important that in some way that you profile any Raw converter to both your camera and preferences, as not everyone likes their colour the same way. I think profiling your cameras is a hugely understated feature of Lightroom and other raw converters.
I would suggest that before you jump up and down about the colours in Lightroom or any other raw converter that you should stop and look to see if a simple solution like creating a profile and applying that as a preset is available. You never know you may realise that you don't like the colours in DPP after all.