Although many of you say you want the "not so big job", you are now complaining that you don't get the respect, benefits, help, office space, etc. that you deserve as an experienced, senior person.  Sorry, but you can't have it both ways - a job that allows you to manage your personal time better and a challenging job!  My advice is to accept the fact that the workplace has changed, and to be successful, you need to consider some behaviors that now are very productive in most organizations.

First, concentrate on the project task.  Most project teams benefit from win/win strategies that value contributing ideas, working together to solve problems and being open to others' ideas and solutions.  Cooperation and collegiality are hallmark characteristics. 

Next, let go of old status symbols like office space, etc.  Go with the flow based on your specific organization's structure. 

Finally, enjoy being self-sufficient - you actually will start to thrive on your own contributions and creations.  Enjoy the fact that you are experienced and highly skilled - use those skills to help your team thrive and produce. 

Change is good and remember you now have time for all those things you like to do outside of work...enjoy!