There were no filibusters at all until 1917, I believe. The greatest Senate speeches were supposedly made prior to 1860, when many senators served short tenures because it was such a sacrifice to spend time from their businesses even though the Senate was in session for just two months a year! Now these senators spend much of their time on the social circuit, as you clearly explained. A really hardworking one like Senator Coburn would be disdained by most of his "lazy" (your word) colleagues.
Well they are lazy.
They are receiving taxpayer funds to do their jobs. I do not care that they are friends with the enemy, that they wish to "sway" the enemy and think they can do it by caving.
They are sent there to do the voters' business. They are not as elite as they think they are and the power they gain is corrupting our government.