After following a link from the Nodes You Wrote listing, I almost always then use the in thread link; I rarely use the in reply to link.

I'm not too worried about having to click a second time; however, during busy periods the double delay of loading two separate pages can be a mild annoyance.

So, having a link to the thread would be useful to me; I'd get very little use out of a link to the parent.

I see two main items to consider with respect to this request:

1. Using the default display of 50 lines, would the generation of an additional 100 links incur a greater delay than is currently being experienced (which probably directly equates to the effect this might have on server load).
2. While it may look like two extra columns would fit in the table, others using smaller screens or larger text may view this differently. Have a look at the recent discussion Could we lose (or turn off)the sidebar during preview? where this topic was raised.